PrinceCon 21 : Waterworld

Director: Mark Krumholz

Fleeing disaster, the PCs and thousands of dependents arrive in a previously occupied archipelago, and must make themselves a home.

Player Introduction

From The Con Director

Fellow Adventurers:

Welcome to PrinceCon XXI! If you have not already done so, please take the time now to fill out your character preference sheet and give it to someone behind the desk; this will help us get things started promptly. Runs will begin at around 5:00 PM today, and adventures will leave continuously from then until Sunday morning. All runs will end by 3:00 PM on Sunday, and the awards ceremony will start shortly thereafter. To go out on a run, just find a GM (they’re the people wearing the PrinceCon t-shirts), a group of people to go with, and come to the desk. We’ll handle the rest.

There are just a few simple rules to keep in mind: first, please be respectful of Whig Hall. We are here only by the permission of the American Whig-Cliosophic Society, which controls Whig Hall. Due to damage to the building and other rules violations in the past, we are on very thin ice with the administration of Whig-Clio. Please do not give them any reason to kick us out. This building is very convenient and we wish to continue to use it in future years, but we will only be able to do so if you treat it with respect. Please do not leave trash on the floor. Please do not sleep in Whig or abuse the bathrooms. Activity like that will get us barred from Whig for the future.

Second, there will be some other groups using Whig during the convention. The Whig Hall lounge, the room on the first floor, is ours for the duration of PrinceCon. However, other groups will be using the Senate Chamber on the second floor while the Con is underway. Please treat these other groups with respect. Do not go into or leave your belongings in the Senate Chamber until the awards ceremony on Sunday. If you do, you will create problems with Whig-Clio, and you will probably also lose your belongings.

Finally, please treat the other rooms you use with respect. The registrar’s office is more tolerant that Whig-Clio, but they will still be upset by a mess. Please make a reasonable effort to clean up when you leave a room.

Now that we’ve said that: have fun! That’s the reason we’re all here.


Mark Krumholz,
Director, PrinceCon XXI


We like to take this opportunity to thank the many people who have helped bring this convention to fruition. The con system is the product of countless people over two decades, but we would like to recognize in particular Howard Mahler, the primary author of the combat and magic systems, whose campaign system started it all. Bob West developed our religion system in 1985, using ideas from his campaign, and edited the changes for this year’s conbook. The mage spell modifier concept is primarily the work of Dan Eisenstein.

York Dobyns and Tim Oliver are responsible for the computer software. Bob West developed the sailing rules for this year. Shantanu Saha prepared the prizes.


Player Theme Pack

The Tale of the Dispossessed

Now, children, hear the tale of the land of Sitnalta, of its downfall, and of the flight of the Seven Kindreds. Full of sorrow and defeat it is, yet also of hope and great deeds. For the Seven Kindreds had among them many great warriors and masters of lore, and many friends of high stature as well. Not all came to fame or renown, or indeed a good ending. But they made many journeys, and saw many things strange and wonderful, and fought many things dark and terrible. In the end, they achieved…well, you can decide just what it was they achieved.

And what of Sitnalta, you ask? Its origins are shrouded in the mists of time, yet it is said that Sitnalta was the first great work of the Seven. It is said that Daglir wrought its bones from the stuff of stars, lifting up the land from the boundless ocean. Danu came and dwelt in it, filling it with trees and flowers and green. Carrunos sent beasts great and small to abide there, that he could therefore be close to his consort. Isaiah Samwise brought peace and healing to the land, that it would not see hurt or sickness. Janda gave it justice, and saw that the land was well ordered. Hione sent forth wisdom, and sought to preserve all that was good. And Leo raised the Girdling Mountains around the rim of the land, to make it unassailable.

For a thousand years the people of the Seven dwelt in Sitnalta, growing ever more in wealth, power, joy, and wisdom. So great was their bliss that they wished to share it with others, and at the feast marking the Millenium, the foremost of all the children of the Seven stood up and declared that they would become Adventurers, to seek new lands and peoples. Then a great work was begun, and ships were built with Danu’s wood and Daglir’s craft.

The Adventurers sailed far and wide, discovered many new lands, and made new friends wherever they went. The bliss of Sitnalta increased even more as trade and communication with these new lands grew. Many people, drawn to the majesty of Sitnalta, came to dwell there, and a great community of immigrants arose in the heart of the land. They learned wisdom from Hione, compassion from Isaiah, justice from Janda, and honor from Lee, though for the most part they chose to keep their own beliefs, and were called Pantheists. Many also became Adventurers. And so it went for another seven hundred years, and was called the Golden Age of Sitnalta.

In the Year 1786, at the height of its glory, the brightness of Sitnalta was dimmed. In that year, the first shrine of Menthax was erected. Not even the high priests of Hione can tell just where Menthax and his first worshippers came from, but they can tell the consequences. As the cult of Menthax grew, the people of Sitnalta for the most part hearkened to his lies, and began to turn away from the Seven. They began to believe that the power of Sitnalta should be used to rule over other lands instead of protecting them, and its glory could be made greater by holding others in thrall. Beginning in the year 1931, the warriors of Sitnalta struck out far and wide, conquering all lands they could find, until all the world that they could see was under their sway. Those that refused to submit were enslaved or put to the sword. The Golden Age of Sitnalta crumbled and the Empire of Menthax arose.

Under the dominion of Menthax and his followers, the peoples of the Seven were increasingly persecuted. The League of Adventurers was especially targeted, and forced to go on voyages of discovery for the purpose of finding new lands to conquer. Those who would not submit were put cruelly to death. Many of the faithful were forced into hiding or exile.

In the year 1995, the Council of the Seven met in its secret hiding place in the Girdling Mountains. Communing with their Lords, they prayed for the gods to show a way to escape the dominion of Menthax. In response, they were told to build twenty-one great ships, three for each sect. The ships were to be large enough to hold 250 people for a long voyage, and be ready to sail by the last full moon of Autumn. They were to be built on the slopes of the tallest mountain in Sitnalta. Perplexed by this command, the peoples of the Seven began their greatest labor in secret, avoiding and misleading the spies of Menthax. Many died in the effort to conceal the building.

Finally, the ships were finished when the last moon of Autumn had grown to half full. The remnants of the people of the Seven gathered at the ships, but could only fill fourteen of them. Then Pelham, high priest of Hione and leader of the Council, said “let the remaining people of the Pantheists populate the last seven ships, for they have ever been our staunch friends in this dark time.” And so the Pantheists came with their families, and the company was complete.

In this time the spies of Menthax learned of the gathering of the last of the Faithful, and the high priests of Menthax sent an army against them. Seeing this from afar, Pelham gathered the remaining men and women of renown among the Faithful and the Pantheists, and led them out to meet the advancing army. The Last Company of the Seven Kindreds performed deeds of surpassing valor, halting the advance of the host of Menthax for seven days in the passes of the Girdling Mountains.

When the last full moon of Autumn rose, the earth began to shake. Deep rents opened up in the ground, and swallowed up much of the host of Menthax. Mountains began to crumble, and the surrounding sea began to flow in. It washed away the last of the assailing army, and the remnants of the Last Company as well. The waters flowed up even to the height of the ships, and the little fleet floated off, carried by the inrushing sea over the dying land of Sitnalta. When the inundation was complete, all that was left to mark the land of Sitnalta were the peaks of the Girdling Mountains, now tiny, dwindling islands circling a great lagoon. In sorrow at the loss of their home, the survivors of the Seven Kindreds and the Pantheists sailed away.

What caused the destruction of Sitnalta? Some say it was the Seven themselves, angry at the turning away of the people of Sitnalta. Some say it was Menthax, destroying the land of the gods that he hated. Some say that it was another force, from outside the circles of the world. The answer will probably never be known.

Reaching the nearest island, the fleet sighted the navy of Menthax returning from the conquest of a far-away island. The Ships of Menthax hoisted sail in pursuit, and chased the fleet of the Seven Kindreds for several days. On the ninth day of the chase, the wind rose and became a hurricane, engulfing the ships of the Seven Kindreds in its eye and destroying the fleet of Menthax. For thirty-six days the hurricane blew, moving the ships of the survivors a great distance in an unknown direction. Finally the storm dissipated, but not before a final great wave washed all twenty-one ships onto a great sandbar, breaking their keels.

Stranded on a desert island under strange skies, the survivors used what wood they could salvage from their ships to build a little fleet of small scout ships, to explore their strange surroundings. Manned by the grown children of the League of Adventurers, the ships set off on the Ides of March, in the year 1996, to find…

It is now the Ides of March, 1996. You are the children of the League of Adventurers. It is YOUR job to find a home for the survivors of Sitnalta.

Good Luck!


GM Themepak

Theme Background

Princecon XXI is an exploration con. The Heroes have fled a natural disaster in their homeland, by way of very large boats. They sailed for many moons, and the condition of the hastily constructed ships steadily worsened. Eventually, they simply reached the end of their endurance. The population is big enough that even having all of the clerics spend all of their prayer points Creating Food and Purifying Water is insufficient to keep up with all the mouths, although it did stretch supplies far beyond anything mundanely possible.

Fortunately, before disaster struck, the MotherShips found land. It is a large archipelago, and they sailed right into it, hoping to find a large enough island. Unfortunately, they didn’t reach a suitable spot before it became too dangerous to continue. So everyone landed on the nearest island, and set up camp.

What with worms and related damage, the MotherShips are no longer seaworthy. Because the initial HH crew wasn’t high enough level to bind, seal, etc., stuff with Lasting duration, and the Danus had no living wood to grow replacements, there was no hope for repair. So the ships were broken apart and the sound wood used to build a lot of smaller ships that are adequate to do island-hopping.

Hireling Sandbar

The PCs and reserve-PC supply have landed on Hireling Sandbar, a low atoll about 6 miles long by 1 mile wide. Most of it is covered with beach grass; a low rise near the center holds a small spring and a few coconut and date palms. There are also large numbers of potted fruit trees from the Fleet.

HS is essentially an unattractive piece of real estate used only as a watering hole until the arrival of the Exodus fleet. Now, it holds some 10,000 people, between the dependents of the PCs, civilian types accompanying the Great Exodus, and the “reserve supply” of replacement PCs. It’s enormously more than the Sandbar can support without heavy magic, work that will probably make magic-capable characters jump at the chance to go off on a dangerous expedition rather than stay with the grueling grind at home. It’s a big enough number that it will be a major task to relocate them once a suitable New Home is found.

Princecon XXI Goals

The basic goal is to find a place to relocate the Sandbar population to by 3PM Sunday. Finding supplies/magic items to stretch out the food supplies, or even make HS self-sustaining in the short run, is a good subtext for early runs. However, even with adequate rations, HS is not a good longterm home, as the effects of Hurricane Zandossa should make clear Saturday night. Here’s a more thorough list:

  • Get a food and water supply from natural sources. Aside from the obvious, this will fix the problem of spellcasters having 0 points at the outset of every expedition, which we will be imposing at the start.
  • Prepare for Hurricane Zandossa on Saturday night/Sunday morning, which the Danus will see coming days in advance. This can involve finding a suitable evacuation site on an adjacent island, fortifying a spot on the Sandbar, or whatever else comes to mind.
  • Find a suitable permanent new home; the evacuation site and the adjacent islands, should be unsuitable for this for reasons left up to the GMs of those localities. The target is to have livable real estate, in quantity sufficient to the dependent population, that isn’t already in use. Unoccupied land that can be rendered arable by PC techniques (maybe the natives don’t have plows) is OK; political intriguing to have NPC societies cede suitable territories to the PCs is OK. Attempts to render occupied lands more suitable by exterminating the occupants should be hosed without mercy.
  • Find out who the new neighbors are, and deal with them if need be. Even aside from finding a safe place to live, there is some value in knowing that Island 75S 143W is infested by hydras and no one sane should land there, despite the numerous potable springs. Also in this category fall the Raiders, which we already have volunteers to run.
Style of the Con

We obviously want to emphasize exploration and also resettlement. It would be a shame if the players solved all of their problems with overwhelming magic. Too many Decanters of Endless Water will really dilute the theme. Be aware of this while generating Item Lists, and be sure to assign a Burnout to anything that could have an undesired result.

Princecon XXI Scenario Ideas

Early runs might be strictly oriented on mapping the archipelago. Groups might be sent out with instructions similar to the following:

  • Explore and map the waters and coastlines in your assigned sector, and record same on a chart or charts suitable for navigational and explorational use. In the execution of these orders, you will avoid unnecessary hazard to your mission, which you shall interpret as follows.
  • You shall avoid landings except as necessary for the safety of your vessel and crew. You shall avoid contact with potentially hostile forces or creatures. You shall take all prudent care for the safety of your vessel and crew, but shall at all hazards return the above designated chart safely to Hireling Sandbar.

It would probably be good to have 1-3 GMs take “Promised Land” scenarios – potential new homelands available in their runs if they crack properly. None of these should be sufficient to relocate the entire population to, but together they can relieve the pressure.

One approach to the overpopulation problem would be piecemeal settlement of small colonies on nearby islands. This might defuse the urgency of exploration in the later con, but on the other hand it’s an endless springboard of scenarios – “Remember that island you reported as `cleared for colonization?’ The one you wiped out all those hydras on? Well, we just got word that about 3 thousand hydra eggs have hatched, all over the island. They’ve already eaten the wheat crop and half the farmers, too.” Read Legacy of Heorot for a sense of possible pitfalls in colonizing an unfamiliar ecology.

Another possibility is caring for the population on HS. If the players get into the theme, this will be a central part of the con. Which means that they may want to be directly involved with how it’s done, beyond simply sailing without spell points. It may be interesting for one DM to volunteer to “run” keeping track of the refugees as his scenario, and let players contribute ideas and items while they are in hireling hall. Possible issues: food, water, shelter, disease, unrest amongst the NPCs, archipelago natives coming to HS to gawk/trade/convert the natives/etc.

Resettlement – We shouldn’t have a solution ready for the players. If there is one island which can support 10,000 people, that scenario will dominate the con. I think the eventually “solution” should have the players and their dependents spread throughout the archipelago, trying to fit into several different niches. If the players “solve” the immediate shelter problems Saturday, we can still throw a bunch of political/security problems at them at their new locations. The new society won’t be built in a weekends worth of runs, so the end of the con won’t have a lot of finality, but for this theme that’s appropriate.

Supply lines – Another amusing scenario idea could take place after some fraction of the refugees were established on another island in a defensible location – but without sufficient access to food supplies. Someone has to defend those food shipments against natives who would rather not have us around…

Princecon XXI Planet Stats

We will use nautical miles (2000 yards) rather than statute miles (1760 yards) for all long-range measurements. The horizon distance for a single person rises as the square root of height. The distance at which two objects (island peaks, ships’ lookouts, etc.) come into view of each other is the sum of their respective horizon distances. Yes, it is possible to have mountainous islands positioned such that their peaks are in view of each other but at the coast each is invisible from the other.

The diameter of the planet is 4 million yards (2000 miles). With that figure, the horizon distance for a 6 foot tall person 2800 yards (1.4 miles). The biggest ships available will have a horizon distance of about 4 miles (assuming about 40 feet for the height of the crow’s nest. Any pair of islands more than 10 miles apart is invisible from midway between, unless they have shore cliffs or significant elevations inland.

Height (feet) LOS (miles)
6 1.4
10 1.8
15 2.2
20 2.6
25 2.9
30 3.2
35 3.4
40 3.7
45 3.9

The Princecon XXI archipelago

With the aformentioned planet size, 1500 miles takes you from equator to pole. With an Earth-like axial tilt (and resulting seasons), about 700 miles takes you from the tropics to the arctic circle.

The Archipelago stretches about 700 miles north-south, a somewhat smaller distance east-west. It’s in the southern hemisphere: the southern islands are arctic, the northern ones are tropical. Island topography is appropriate to climate. The islands will be sized as follows:

Class Size Example
Tiny -5 square miles Statue of Liberty
Small 5-25 square miles Little Cayman; Key West FL
Medium 25-150 square miles Washington DC; Manhatten NY
Med/Lg 150-500 square miles Nantucket & Martha’s Vinyard
Large 500-1500 square miles Oahu; Maui; Truk Lagoon?
Big 1500-5000 square miles Long Island; Hawaii; Cape Cod
Huge 5000+ square miles Paupa New Guinea; Greenland

Minimum island distance: Zero, provided the same GM runs both, or the GMs running them agree to close linkage.
Minimum separation of non-linked islands: 10 miles.
Maximum island separation: 50 miles.
Mean: 20 miles. These refer, of course, to “nearest-neighbor” separations or the widths of channels between adjacent islands.

Princecon XXI Islands


We simply don’t want ongoing, regular trade among the islands as a whole. It would hardly be a challenge to map the archipelago if there was already a bustling maritime society there. However, regular maritime trade between two or more islands is a perfectly legitimate option for GMs who want to link their scenarios that way. We can have a reasonably advanced civilization without having a seriously maritime culture that unifies the whole Archipelago.

Inter-Scenario Travel

Parties could reasonably sail or be blown off coure, and land on an unintended island. Unless GMs plan these events between themselves for neighboring scenarios, that unintended island must be part of the GM’s scenario rather than someone else’s. For this reason, keeping the islands belonging to separate GMs reasonably well separated is a desirable feature, but on a scale of tens of miles, not hundreds. Beyond that, we’re left with the “gentlemen’s agreement” of past Cons; parties aren’t to wander into other scenario territories.

Inter-Island Travel

Exact modifiers aside, a pair of MU7′s or a single MU9 can greatly facilitate travel between islands. With a combination of levitation, flight, and/or weather manipulation, one could transport a boatload of people, plus boat, a great distance in a couple of hours. It’s up to the GMs to discourage this, with strategically placed “random” encounters on landing. They may be able to travel between moderately close islands this way, but they may not arrive with full spell points…

Princecon XXI Map and Mapping

Online Maps
Map Description

The map will cover the entire archipelago. At the beginning of the con, the only part that will be revealed is the path the MotherShips took from the open sea to Hireling Sandbar. As the players explore the archipelago, new map sections will be posted.

The origin of the map will be the center of Hireling Sandbar, with North and East being positive directions and positions being given by two coordinates given as Longitude (east-west) and Latitude (north-south). We will ignore curvature of the planet effects on distances between places. Thus all lines of Longitude and Latitude will be straight.

Between GM-run islands, there will be small watering stops. As for preventing PCs from monopolizing a spring – the occasional war canoe full of thirsty high-level headhunters (or, if you prefer, dragonboat full of thirsty high-level Vikings) should amply discourage would-be squatters.

Please be aware that we are not demanding a 1-1 correspondence between GMs and islands. Preferably no one island should have more than one GM running it, but there is no reason a GM shouldn’t run as many different islands as he wants. The only constraint is taking some care with the geography so that two parties don’t demand the same GM at the same time.

Finally, note than islands close to Hireling Sandbar should all have good reasons not to be New Home. Hostile/dangerous inhabitants on an otherwise suitable locale will do in a pinch, as we can then have repeated attempts to clear out the nasties while exploration parties continue to seek elsewhere in hopes of finding a site that’s less of a fixer-upper.


We’ll provide players with grid paper, and allow them to map for themselves during each run. Part of exploration is getting lost, or following a map that leads you into the middle of nowhere, so we don’t want to make cartography too automatic.

However, Hireling Sandbar will ignore inaccurate PC mapping. So long as they are reasonably accurate, hand-drawn maps will be surreptitiously replaced with computer printed ones for the official map in hireling Sandbar. If their maps are completely confused, the resident Clerics will inform the group that the gods have revealed that their map is in error, and no additions to the official map will be made.

Of course, GMs are free to distribute erroneous maps from other sources, if you wish to intentionally lead the group astray.

Princecon XXI Natives

As mentioned, the natives of the archipelago don’t have an extensive seafaring culture. There is travel between neighboring islands, but it is all rather limited. The only groups with extensive seafaring experience are the raiders.

The raiders will act as a disincentive for islands to indulge in heavy sea travel, if the GM hasn’t come up with anything internal to the scenario. We’ll include intelligent raiders as a common sea encounter. But they won’t be so ubiquitous that it’s seen as the kill-the-raiders Con. Also, there will be more than one group of raider, distributed geographically. Among other things, this would give the raiders an extra incentive to attack unfamiliar ships they spot at sea: kill the competitors! Finally, do not overlook the possibility that the PCs could become pawns in existing territorial struggles. The northen raiders may be quite willing to help the PCs set up an encampment – in southern raider territory.

An important thing to consider is the power of the natives. Extensive discussions have raised several examples of advanced cultures that didn’t take advantage of nearby bodies of water. GMs are encouraged to find reasons for natives to stay away from the sea without making them hopelessly primitive.

However, even if the natives are relatively uncivilized, this does not mean that they are necessarily pushovers. The “primitives” could nevertheless be exceedingly nasty customers. Imagine, just as an example, a culture based on a melange of South Pacific peoples. Yes, that raiding party closing on you in a dugout canoe is armed with stone-tipped spears and arrows, and wears no armor. The trouble is, they’re all 7th level fighters, they’re all wearing +5 Amulets of Protection (which every boy learns how to make for himself as part of his manhood initiation; you have to make your own amulet if it’s to protect you, so there’s no problem with PCs capturing gross magic items), the stone points on their spears are +3 Spearpoints of Human Slaying (again, wielder has to chip his own points), and the guy in back with the fancy paint is throwing Finger of Death spells out of his innocuous-looking pointing bone. Most “primitive” cultures do not make the fine distinction that we do between “mundane” and “magical” effects. To a Polynesian canoe builder, the right songs and chants are as important a part of making the canoe as is carving the log to the proper shape, or fastening the outrigger correctly. All we need to do is make that worldview real for the natives, and the “primitive” aborigines can be a challenge to the toughest Sunday-morning parties.

Princecon XXI Navigation & Weather

Currents & Hazards

There will be currents on the scale of the entire archipelago. GMs are encouraged to take these into account, since they will be constant across an entire scenario. We will also have local currents and navigational hazards such as reefs. GMs are free to use or ignore these as they see fit.


Basic navigation is a skill most of the characters will have picked up on the long journey to the archipelago. Mages have spells that can be used for similar purposes: Find North, Locate morphic spell, etc. Danu clerics are, at least in concept, landbound, although it probably does make sense to allow them to communicate with sea life as they do with land life. However, sea life is generally indifferent to exactly where they are, which makes navigation somewhat problematic. (Yes, there are exceptions who find spawning grounds, etc., across tens of thousands of miles. A Danu cleric can probably talk to a turtle and find out where the good feeding shoals are and how to get to the hatchery beach. This is still not going to be terribly useful unless those are relevant to landmarks of human interest.)

The idea here is that we will not force players to explain exactly how they use the stars to figure out which way they’re going. We’ll assume they can navigate, and we won’t be terribly strict about it. You’re welcome to periodically force them to use their magic (a cloudy night), and of course allow them to make mistakes in mapping, but no serious hassle.


There will be pre-generated weather for the entire Con. The basic scale here will be one day per hour of real time. GMs will get a weather list for 12 days (12 hours) upon departure. If a run is going to be especially lengthy, the GM can request extra weather, or simply stretch the given weather to fit the length of the run. The one major “landmark” is going to be a typhoon at 3 AM Saturday.

Princecon XXI Expeditions

It is to be assumed that locales farther from HS, be they scenarios or only portions thereof, will be reached later in the Con. A possible alternative to revealing island locations only as their neighbors are reached is for some GM to take the “Magellan expedition” – the best boat we have, with crack sailors and expert adventurers, is sent out under strict orders to make no landfall; just locate the coastlines of major islands. Some GM could then run a scenario consisting only of mapping and assorted fun ocean encounters, and send groups back with new sections of map to post – sections that include only the outlines of islands, not the interiors.

A list of increasingly urgent disaster measures will be instituted by the command at Hireling Sandbar. This will be alleviated if the players are particularly successful, and aggravated if they particularly obtuse. In the beginning, all characters who are capable of casting Growth Plants, Purify Water, Create Water, Create Food, or related spells are assumed to spend all of their spell points doing so as long as they are on the Sandbar; all magic-capable characters set out “empty” (no spell/prayer points) at the beginning of their first day of travel, with no opportunity to set up lasting spells in advance. (A non-portable item allows transfer of spell points, so no weaseling out on the grounds of being too low level.) We’ll post further effects here as we come up with them, but it will include things such as: not only will initial parties be de-spelled, they’ll have no food or water on board ship, and will be suffering hits of damage and Constitution penalties due to hunger/dehydration.

One final note: With the resupply available at Hireling Sandbar, and the periodic watering points,we don’t need “mundane item” cards. Each GM can handle the issue of food, water, etc internally to his scenario.

Princecon XXI Sample Islands

Since we don’t want extensive seafring cultures, we’ll need some reasons for individual islands to remain isolated. Here are some samples of why an island may be little visited, or puts out few or no travelers:

  • Manticore Island. More of a one-shot encounter than a scenario, but bear in mind that GMs may have a “scenario” spanning as many islands as they want. Obviously the manticores don’t build ships. And no one in their right minds wants to land there….
  • Easter Island. Like the actual Rapa Nui of Earth, the natives of this island, over centuries, cut down *every* tree big enough to build canoes from. After the last canoe rotted, they were restricted to swimming distance from the shore. They no longer leave home, except for the occasional hero who tries to visit….
  • Elf Island, the only other land in sight of Easter Island. It does still have trees, because the inhabitants are typically ecology-conscious Elves. It is also paranoid and isolationist, because for the last 500 years the only outsiders the Elves have seen are brawny barbarians swimming over from Easter who are intent on chopping down big, healthy trees to make boats. The Elves now strongly discourage visitors (as in: pincushion treatment), and have no interest in visiting other islands.
  • A culture of superstitious natives. A recent King died in a fishing accident, and they have determined that the God of the Seas is displeased with them. Thus they are all afraid to leave the island, until they can find some sacrifice noble enough to appease the mighty God. Of course, invading adventurers might make a worthy sacrifice….

And so forth. Each GM is allowed to come up with his own rationale for why the island(s) in his scenario does not impinge significantly on other islands.