The geography of Guantanamo Bay is remarkably diverse. In addition to the arid hills, where Tolson has studied the hutia, the base is surrounded by water--the bay itself, and the Caribbean Sea. The coral reefs and coastline are considered among the most pristine in the world, says Tolson. Along the base's sandy shores, the herpetologist Lemm has studied Caribbean turtles' nesting habits. Researchers aren't the only ones exploring the base's beaches and waters, though. A tour at Guantanamo Bay is considered hardship duty for servicemembers, who can acquire their scuba "divemaster" certification for free as a benefit of their service.