Near Grand Case Bay off St-Martin, the snorkeling at Turtle Reef is a well known for its namesake green sea turtles and hawksbill turtles. At this circular reef, the water depth ranges from 6 to 25 feet deep. During Turtle Reef snorkeling, you may encounter toadfish, frogfish, octopus, stingrays, eaglerays, flying gurnards, hawsbill turtles and green sea turtles. While this boat-accessed snorkel spot is one of the best on St Martin, it can be very difficult to find so make sure to go with a charter boat service.
To reach the snorkeling on Saint-Martin by air, fly into Princess Juliana International Airport (SXM). Note, there is a $30USD departure tax collected at the airport.
In addition, there is a ferry called Great Bay Ferry that interconnects St. Martin with St Barts.
Overall, Turtle Reef is the 3rd most popular snorkel dive spot of all 9 snorkeling dives in St Martin.