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 10 snorkeling dives in St Martin.