Off the western point of St Martin, the snorkeling at Baie Rouge is very popular with local snorkel divers.
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, Baie Rouge is the 9th most popular snorkel dive spot of all 10 snorkeling dives in St Martin.