I'm working on updating an older campaign setting think an ocean world not quite Waterworld there are islands some quite large but not many big ones, think British Isles is BIG and most land masses are more a few miles wide.
So knowing how to swim is a big deal and note metals are uncommon to rare so thinks like weapons using it costs a lot more than in the book a longsword usually costs 150 gp. But none metal weapons are used Sharktooth Weapons, clubs, staves and so forth. Armor is also affected but if you want to wear chain mail on a ship go ahead. Magic items are uncommon think around but basically potions of healing and such can be found and spell user are more uncommon but not disrespected I'll allow one arcane user and one divine user in the band since your special.
If anyone is interested it would start at Level 2 and your going to know each other being raised in one of the floating atolls think a village that floats and is anchored in place well the meet at the tavern and decide to go off adventuring. And your going to get a new ship, well a sailing schooner, suited to a small number of people.