Did not Do the Research

I have just invented salt-water dwelling relatives of hippopotami (to the real world version what salt water crocodiles are to their freshwater cousins).  What would be the best way to name them? They live in a Sargasso like area.  Actually, is there a general term for that kind of oceanic area?  I should find that out.

THALASSOPOTAMUS.  (GRAAH!) 
Awesome.

The Sargasso Sea is not as advertised.  That's okay, in fact, I can come up with something analogous.  Like a giant weed-choked cape.

Also, these were not invented for MFP, but they are totally going in.  Motherfucking Thalassopotomi.