A water-based scenario book for TT would be cool.
Random ideas to knock about:
Pirates, ship boarding actions
Pirates, hidden treasure maps, with or with out mystical curses
Defending ports from sea borne attack
Fishing for profit, regular and extreme (catching whales and giant squid, squids?, squidi?, what do you call more than 1 giant squid?
Ship navigation (getting lost and having adventures there)
Atlantis, inhabited by fishmen or crabmen (or both!)
Diving for stuff, shark attacks!
Lighthouses, ummm, worth mentioning but I'm not sure how that would fit into the rules
Water hazards: whirlpools, water spouts, crashing rocks, kracken attacks, shallows, rip tides
Sargasso sea, area of circular ocean currents that trap ships, wrecks, lost cargo, trees that washed away into the ocean, etc
Deserted islands, lifeboats and rescues.
There, I've done all the hard work, now somebody put a rule book together.
Diplomacy is the weapon of the civilized warrior.
-- A. T. Hun (Robert Aspirin)