These are red-mangrove (Rhizophora mangle) proproots, in the Bahamas as in the previous image, but southeast of the previous site, on a cay at the Atlantic-Ocean edge of the Bahamas, on the eastern side of Exuma Sound, between Eleuthera and Cat Islands. The substrate appears white in this image, because it is made up of myriad little pieces of broken shell. We had to pound through big surf to get into this inlet, and we saw two big bull sharks as we were getting out of our Avon.