Asan Reef – Hagåtña Bay & Asan

18m Max

15-30m Vis

shore

Site Overview

Asan Reef is a gently sloping coral reef renowned for its exceptional macro biodiversity and its role as a known cleaning station for green sea turtles. The reef descends from approximately 3 to 18 metres over a varied substrate of coral bommies, sandy patches, and rubble areas that create diverse habitat for an extraordinary range of small marine species. Pipefish, frogfish, and seahorses are reliably encountered among the coral formations, while nudibranchs of numerous species display vivid colours on the reef surfaces. The site is particularly famous for its green sea turtle cleaning station, where turtles hover motionless while small wrasses and gobies remove parasites from their shells and skin. This natural behaviour provides divers with unforgettable close-up encounters with these gentle creatures. The shallow depth and calm conditions make Asan Reef ideal for macro photography with extended bottom times, training dives, and guided snorkelling excursions. The reef is accessible as a shore dive from Asan Beach Park, making it one of the most convenient macro diving sites on Guam. The reef has been monitored by marine biologists for over a decade, providing valuable data on coral health, fish population dynamics, and the effectiveness of marine protected areas in tropical island environments. The diversity of nudibranch species recorded at this site exceeds thirty different types, making it one of the most species-rich macro diving locations in the entire Micronesian region.

Dive Briefing

"Enter from the Asan Beach shore access and descend to the reef at approximately 5 to 10 metres. Work your way slowly along the coral bommies, scanning carefully for camouflaged frogfish, seahorses clinging to gorgonians, and pipefish hovering near soft coral colonies. The reef slope transitions from dense coral coverage in the shallower sections to scattered bommies on sand at greater depths. Look for the turtle cleaning station, typically located on a prominent coral bommie at approximately 8 to 12 metres. Green turtles visit regularly and should be observed from a respectful distance without touching or chasing. Nudibranchs are abundant throughout the reef, with multiple colour variations represented. Maintain excellent buoyancy to protect the coral formations and avoid stirring the sandy patches. The dive typically lasts 50 to 60 minutes at these comfortable depths. The cleaning station operates throughout the day, but turtle visits are most frequent during the morning hours when the reef is bathed in warm sunlight. Patient observers may witness multiple cleaning interactions during a single dive at this remarkable natural spa facility for marine life."