if going to trunk bay, go clear down to the left, facing water, great snorkling there. i personally think cinnimon bay is to windy, hawksnest to hard to navagate thru the coral. i personally like big maho bay, easy in easy out. park car walk ,cross the street and your on the beach, go clear to the right while snorkling and out around the corner. seen about every think i can think of there. shallow water for about 5 to 10 feet out. if u have time and are strong, try haulover bay, walk down the little path, dont know how far, but watch out for the barbed wire on the ground
, no sand on the beach, hard to get in and out, but its an awsome sight, even staghorn coral over to the left. i go straight to st john, st thomas isnt near as pretty. never heard of any snorkling in san juan, not so sure the water is that clean. maybe soemone can correct me on that part.