I packed my own snorkel... self-proclaimed germaphobe.
My globetrotting friend lent me her waterproof Nikon Coolpix S31 that she bought specifically to take underwater pictures on vacations. It got the job done for the beach. I would recommend this over a waterproof phone case so you aren't stuck with something incompatible down the road.
My other photos were taken with a Nikon D3200. I purchased mine from Costco.