I'm swimming from point A to point B. I'm doing a mission in water. I'm picking up some Stranglekelp (actually most of the time it's that one). For whatever purpose I'm in the water, I love finding the undersea version of a treasure chest.... the Giant Clam:
It's not exactly treasure inside, just some clam meat, although there is the occasional pearl. This WoWWiki Link shows in an easy format which areas drop which kinds of pearls.
You may know about the Dwarf racial talent to find treasure. Well, it identifies not only treasure chests, but also clams.
Here's a photo montage of my adventure trying to establish that my dwarf's treasure finding skill will indeed find the clams:
Oh yeah, don't forget about the reef sharks. The picture above is from Westfall. An elite level 22 (very high end for Westfall) patrols the edge of the reef. How's that for a deadly surprise? And here I thought doing my duty in Westfall was killing those roaming elementals.