OK so after seeing the really amazing Deep Sea Divers by Scheltrum Miniatures, I started to wonder what miniatures are out there that would be good foes. I have come up with a few.
Naval Pattern Type D Divers
Gentlemen Adventurer Treasure Hunters
Free Company Privateers
Dr. Octopus's Squid Pirates
DragonRune Miniatures Komodons
http://www.dragonrune.com/DRHome/The problem with the Komodons IMO is no one has painted them to the standard that they deserve, so they don't show well. I haven't seen one yet painted to a high standard. Let me tell you that these figures are absolutely gorgeous in person.
A shot of a green Komodon
Privateer Press put out a really nice miniature set recently for their Hoards game. The figures are called Bog Trogs Ambushers.
Reaper Miniatures always seems to have a bunch of figures. They came out with a blister of 03161: Slithe Raiders. That are pretty sweet. They also have really nice seahorse.
They also have a really cool shark moster like figure
Way back when Citadel put out some cool figures called Sahuagin
There is another company that I can not remember who made/makes Sea Horse riders and things of that nature.