While this is clearly not the big sport of this area, Dolphin Dive Center (tel. 809/571-0842, www.dolphindivecenter.com [1], 9 a.m.β1 p.m. and 2β6 p.m. Mon.βSat.) can arrange for transfer to the nearly 20 dive sites within a 20-minute boat ride, including underwater tunnels and canyons 25 meters under the surface. It is a popular place to see eels and angelfish. Experienced divers will be able to dive the freshwater caves near Cabrera.
One dive is US$46 with full equipment provided. Dive packages start with a Discover Scuba Diving package for US$50 (minimum age is 10) that will take place in a pool or pool-like condition. Next up is the PADI certification course for US$219 and all the way up to instructor courses.
Links:
[1] http://www.dolphindivecenter.com