Desecheo

Desecheo sits about twenty kilometres off the west coast, a steep uninhabited island in the Mona Passage where the water is routinely clearer than anywhere else around Puerto Rico, with visibility often past thirty metres. Boulder fields drop away from the shoreline into deep blue, with swim-throughs, big coral heads and dense fish life, and the sites carry names that describe them plainly enough, Candyland and Yellow Reef among them. The island itself is a national wildlife refuge and landing is not allowed: it was used as a bombing range and unexploded ordnance remains, while a long-running project has been removing introduced rats and goats to let the seabird colonies recover.

What you actually see

• The visibility - routinely the clearest water in Puerto Rican waters.
• Boulder swim-throughs - the underwater terrain the island is known for.
• Dense fish life - schools over the reef in unusually clean water.
• The refuge - seabird colonies recovering after invasive species removal.

When to go

December to April has the calmest crossings and the best conditions, though winter Atlantic swell can shut the passage down for days. Trips are cancelled often. Summer is calmer but less clear. Book flexibly and allow spare days.

Honest expectations

You cannot land: the island is closed for safety and conservation, so this is a boat and dive trip only. The Mona Passage is open water and the crossing is frequently rough; seasickness is common. Trips cancel regularly and refunds vary by operator. Diving here suits intermediate divers upward because of depth and current.

Nearby

Rincón is the main departure point; Aguadilla is the alternative.