Giant Water Bug

Habitat:

Found on a beach in saltwater surf, but I don't think that it is their habitat. Habitat not well known seems to occur in ponds and swamps with abundant emergent grasses and underwater vegetation. Primarily in the southeastern U.S.

Notes:

I spotted about 12 or so of these bugs at the beach crawling around the wet sand some swimming right at the surf line. I'm pretty sure these bugs live in fresh water, and I've never seen them at beaches before. I wonder if they were blown here by a storm (it was a stormy day) or somehow were washed from a freshwater habitat into the bay.