(said with a flat affect)...If you've never done anything with ships before, why are you running a sea-borne series of adventures...

Well, actually, a better question is: what do your players want? Are they (1) treating ships as just a means of getting from one locale to another, or are they (2) designing gun emplacements and working out tactics for defence against pirates? Or, are they (3) studying up on historical sailing vessels, trying to purchase triangular sails for the mizzen mast, and continually referring to the vesel as a "sloop"?

If your answer is (1), borrow adventures from classic TRAVELLER products. (TRAVELLER planets are essentially islands, anyways.) If (2), then decide if you want to run (2a) ship to ship combat, or (2b) marine boarding parties. I greatly prefer (2b), because (2a) is a bunch of people rolling dice, moving ship figures on a sea-blue hex mat, rolling more dice, and then the entire party dies when the ship gets blown up.

If the answer is (3), then you're in trouble. You're going to have to do research. My first recommendation is the TIME-Life Mariners series of hardcover picture-books.

I'm not planning to do full-on pirate ship warfare, just some basic things, because it's a change from cavern crawling. Cavern crawling gets old after awhile. And most of the shipbound treks are going to just be for mobility purposes, not for full-on fighting. If nothing else, I'll just run battles normally but tell them they're aboard deck and take a -1 to all things that apply to dexterity.

I was more looking for a full-on flavorful miniworld centered around an aquatic atmosphere than just ship warfare. That was only one element that I could think of attempting, if it was simplistic enough. Variety is the spice of a good game, though.

( As an asside,
Ship boarding parties are a Rogue's paradise.

A rocking ship would require the characters to frequently make Balance checks.

If you don't have 5 ranks in balance, you lose your dex bonus to your AC when you have to make a balance check to retain your footing EVEN IF you make your balance check.

...

)

This may be an obvious suggestion, but what the heck...


An island with a shrine to the God of Travellers. Either on a small island by itself or on a larger island with a village built around the shrine. It could either be a forgotten island for the PCs to discover or they could be required to make pilgramage to the shrine or any number of other adventures.

7th Sea is a game that is very similar to the White Wolf system, and is set in a world that uses sea-travel more heavily. You may want to check them out, see if you can find an adventure for some ideas. 7thsea also has an lj community.

AEG adapted their original 7th Sea Game into a D20 version called Swashbuckling adventures, Black Ash Island, is a module with the original rule set. Conversion not to difficult. Posted mainly to clairify for those who might get confused :) My family enjoyed Swashbuckling Adventures.

The Mystery of Black Ash Island looked promising... I know its not d20, but it shouldn't be that hard to adapt...

Also, the URL of the page with a bunch of adventures is http://www.swashbucklingadv.com/resources/

hmm.

Sea sylph/sea elf/ Naiad/ other good water species-Sanghuian/Sea Giant/someotherspecies war.

Sanghuain boarding parties! forcing sides! politics and buying offs. :d mmm.

The 101st Island - either it's one of those giant turtles that you don't realize isn't an island until it's already sinking, or it's a raft the size of a city, continually shifting and growing and shrinking as the gypsy/pirate/merchant people who live there moor and unmoor and go about their business.

Well, I ran a Pirates of the Caribbean themed D&D game for a while last year, so I'll lend you what I had. In my world the biggest producers of ships were elves and dwarves and humans were second or third-class for a change. This in mind, the ships were either fast and sleek or sturdy and unsinkable.

Most of the combat was island-based and rarely did they get a chance to use the cannons on board the ship. I'd love to get a look at the rules in d20 Past regarding pirate ships and the like, but the book's not out for another week or so.
I was able to drop a few One-eyed Willy style dungeons on an island from time to time, but the hardest thing to take into account is that most of the place would be flooded if it got too deep.

I had lots of encounters with sahuagin, locathah, but mostly with seabound undead like lacedons(ghouls) and skeletons are welcome anywhere. Actually I ruled that all Skeletons in my game were intelligent and couldn't be created with Animate Dead, just for a PotC feel. I also made a variant of the ochre jelly that was only interested in fermenting fruit and absorbing rum. It didn't have the ability to harm the sailors directly, but threatening their rum(and fresh fruit) was incetive enough.

Rival pirates also showed up a good deal. One of my biggest sets of encounters was an island that used to hold a temple to a good deity that had been taken over by a black dragon and a vast band of evil-deity-worshipping pirates. Lots of puzzles built into the place designed for good guys to get through topped off with a black dragon using the water in its cave as concealment.

Okay, so I've never gotten the chance to run a high seas campaign, but I've always wanted to and I've put a few ideas together for it.

Firstly, if there is any combat on the ship, depending on the way the waves are rolling (and you'll have to actually pay a mind to the weather out here, don't forget!) everybody is required to make a Balance check, or be forced to spend the round (or at the very least, a move action) to try and stay upright. Anybody that's in potential danger of falling from where they are (the rigging, or by the railing if they screw up bad enough) falls over-board. Balance is always important for sea going types.
Therefore, anything that could potentially rock the ship, either because of an explosion, hit (say, from a Kraken), or because some freak wizard decided that calling up a blizzard would be a good idea, Balance checks all around (set an arbitrary DC, based on how badly the waves/ship is rocking/rolling).

That's to start.

Secondly, always remember that the PC's will essentially be fucked if the ship they're on is ever destroyed. The good thing about ANY pirate is that they'll only blow up a ship if they've no intention on taking anything that's on it, or if they just have to make a hasty retreat. Any sailor worth his salt in sea-water (ha ha) would know that basic principle, and steps can be taken to prevent that from happening.
Monsters are another story, they may or may not want to destroy the ship just to see it crack, depending on what's attacking the ship. Anything of animal intelligence would opperate on natural instincts. Therefore, if you have a Gargantuan shark that you want to throw out against the party...it's going to eat the ship.

Remember that where there are pirates, there are pirate hunters. Any organization or government that has the resources and manpower to do so definately would, because in any close-knit island setting, trade is one of the main sources of power/wealth. Corsairs might be another issue (governmentally hired "pirates" preying upon the trade/military ships of a rival government/organization). Get all of this established and in place before you run the actual game.
If you decide that the pirates in the region are out of hand, just remember that the wealth level and general style of living will be much less than it should be, as pirates tend to...bring down the levels of the neighborhood. :]

Island hopping: Any civilized islands, or islands under the dominion of a nation with a powerful wizardly presence should have a system of travel set up that's much easier than sailing. Namely, teleportation gates or something of the like. It only stands to reason that any magic user would rather travel to an island instantaneously rather than risk the much longer journey. On that same note, the self-same magic user can make a great deal of cash offering his/her services to others. If all the islands aren't explored yet, then some of the islands are beyond the reach of teleportation as nobody has been there yet.
Determine if an island has access to magical transport or not, and remember to set a price (or prices) for teleporting between the islands. There may even be a guild based solely on the teleportation of travelers between the islands (I'm thinking of the Wayfarer's Guide PrC from Complete Arcane) that will give better prices than others. Figure it all out to suit your own campaign.

Hmm...I can't think of anything else to add. :D Hope that helped, at least a little bit.

As a classicist, I have to recommend some reading in the Odyssey for island fun. How about an island with an addictive drug (Book of Vile Darkness has a few fun ones) and the many lost souls who partake of it? And sirenes and harpies and cyclopses, oh my!

Other fun ideas for islands: slightly planar islands (like with minor versions of planar traits), islands where magic just doesn't work or is funky, islands with degenerate primatives living in the ruins of an older (perhaps totally different and weird, like mind flayers) race, an island inhabited entirely by intelligent and rather philosophical constructs, the classic (and already suggested) turtle island, an island entirely inhabited by giants (or conversely, tiny people), an island frozen in time, a totally abandoned island with a stronghold on it--set aside by the sea goddess,perhaps?--maybe an island made up of old ships and such all tied together and built into a pontoon city full of bandits and outlaws. The possibilities are ENDLESS! Dammit... now I have to throw this stuff in my game. Not to steal your idea or anything, of course. Cool stuff!

I used the Seafarer's Handbook published by... um, I forget. One of those companies that does d20 stuff. It's pretty good, but the ship combat rules are a little clunky. The campaign I ran had the PC's getting on a ship to go to a far-off land seeking employment. They were captured by pirate enroute, and after being put to work as slaves for the pirates, they managed to escape, stealing a single-masted boat and sailing to another island. Unfortunately, a boatload of orcs shot a flaming arrow at their sail for fun, and they had to take turns swimming behind the boat and pushing it.

Eventually, they managed to capture a full-size pirate ship, and ended up selling it for a good chunk of change.

An island-based idea I had was based on the movie "Escape from LA," where the PC's have to enter an island of exiles to retrieve some item by a certain time. It's just an idea, though, that I've never fleshed out.