It is going to cost you about $15 per taxi to get to and from Playa San Francisco. Playa San Francisco adjoins Paradise Beach and both can offer you snorkeling trips. Playa Mia is about a ten to fifteen minute walk up the beach from Playa San Francisco.
Another option would be to go to Playa Palancar and take their dive boat for a snorkel trip.
Have a great day in Cozumel..