Last time I looked, there were no fish, corals, hermit crabs, copepods, or anything else besides humans in the local New York beaches.
Those humans were throwing plastic, cigarette butts, soda bottles, junk food into the sand. They were carrying soap, shampoo, shaving cream, and who knows what else into the water. Boats near the shore leave petroleum residue in the water and sand.
I wouldn't want any of the above in my tank. Just thought I'd get a couple of kicks in while you were down!
Andy