Need Ideas for Tomorrow's Game

The party is leaving tomorrow on a long ocean voyage. They're leaving town because of their enemies and their destination is an island promising great riches when they get there.

I've been spendig a lot of time preparing the island. Plus, it's not really ready for "prime time" yet.

In the meantime, i'm looking for stuff that can happen en-route. Preferably on the ship. I could throw a pirate attack at them sometime or perhaps a sea monster of some kind. I'm saving the 'shipwreck' thing for the destination or the return trip, if at all.

Any ideas greatly appreciated...

Flying foes. (A nice Evard's Black Tentacles on deck, or perhaps a Qual's feather token - oak)

Bad weather.

Scurvy.

The cook sucks.

Hope that helps,
Greg

Have them encounter a religious cult en route... One that press-gangs victims into its (un)holy slave-galley...

The PCs can encounter them in fog, get temporarily caught by the baddies, escape, free the slaves, re-encounter their own vessel later at a watering and provisioning point. Make sure the leader of the cult has an opportunity to escape and possibly become an arch-enemy.

Holy fanatics can often be more fun than unholy ones...

There is a slight division among the crew on the ship they are on. Their enemies have paid off one of these groups to frame the PCs. There is going to be a grsly murder and the PCs are going to be framed for it. Justice is fast on the high seas, you either hanging from a yard arm or fish bait. That captain is the judge, jury, and exicutioner.

They run arcoss a derileck ship just floating in the tide. The captain wants to investigate because anythinbg of value found is his to claim. The boat is called the Bounty Bay (or any other erie name that the PCs will recongize as bad). You can have an undead ship, or present a mystery of what happened to the crew?

Storm. Have them hit with a huge ocean storm. Some of the crew gets throuwn overboard and the PCs need to help or else all is lost. Do they try to rescue the sailors or batton down the hatches while they listen to the cries of those who went overboard?

Have a freak storm blow their vessel off course, into an area reputed to be very much like today's Bermuda Triangle. There, the ship can run aground on an island inhabited by some tribe of horrible, cannibalistic demi-humans who worship some form of sea/avian monster.

The party will have to live for a day or two by their wits (keep the weather bad enough to hold them for a short time) and avoid being eaten by the islanders. Then when the weather breaks, have them face the pagan god/monster as they set sail.

Sirens, luring the sailors to their doom...

Friendly mermaids and jealous mermen!!!!

An unexpected underwater adventure.

Depending on how much time you want to spend at sea with them, you can have them get lost (REALLY lost). They end up where they think the island should be but--no island, so where are we?? Massive storm, unusual weather (drunk navigator--PCs should have paid more for a better ship, right

Attacks from under the sea (sea elves/sahuagin whatever you have in your campaign). A sea druid.

They encounter another ship coming back from the island with all the treasure already on board. (If you're feeling mean, and what DM isn't mean )

A mutiny on the high seas can be great fun. Have the crew revolt against a cruel tyrant of a captain, or have the crew really be pirates bent on taking the ship (ala Treasure Island). Either way the PC's have to choose a side, no one stays neutral in a mutiny!
The roleplaying a solution can be great. Then have a standoff where each group holds a part of the ship, builds up their defenses and plays a game of Mexican Standoff.
I was going to run this scenario in my High Seas campaign, but the party went and got themselves all dead by a guardian naga...

Fending off a pirate attack is always fun but usually not a whole night's adventure.

The 2e ravenloft module Ship of horrors is free for download from WotC and starts out with going on a ship anywhere and pulls the pc into the adventure. The module must be converted and parts of it need to be fleshed out and parts revised completely but my group thoroghly enjoyed the experience. If they survive the adventure they can continue the voyage. It generally takes more than one long session to finish the module, however.

I think Atlas has a sea voyage adventure as well, but I don't own it and can't comment on its appropriateness for your stated needs.