Even more ideas:
Divers theme!
1.Research Station
Includes the research station,a small ship,an ATV and 5 minifigs(2 divers,1 captain,1 crew mate and a mechanic)
Prize:40$
2.Ocean Explorer
Includes big research ship,small sub which can be launched from the ship,a little reef with a shark and some crabs and 6 minifigs(3 divers,1 captain,1 crew mate and 1 mechanic)
Prize:50-60$
3.Ship Wreak
Includes ship wreak, a sub,a boat,some sea animals(sharks etc.)and 3 minfigs(2 divers and 1 captain)
Prize:25$