An event during which the sea is turned to grog. Players would get drunk whenever they enter water, but drunken state wouldn't lead to vomiting. Players could still vomit if hit by a magical cannonball, however. Bananas would no longer recover health. Instead, drinking grog would. One full tankard would be equal to 5 bananas. If a player became sober, they would start losing health akin to drowning.
These are the possible rules for the event. A result of this would be players practically impossible to kill when in water. This could be solved if only drinking from a tankard counted as healing, which would in turn require grog barrels to be distributed throughout the islands. On the other hand, if players would get healed when in water, it would be impossible to drown, which could be used as a basis for some sort of underwater treasure hunt on a larger scale than searching a ship wrack. It would also be a good opportunity to somehow utilize the uneasy controls during the drunken state in a quest requiring accuracy, though I have no concrete example to give.