The Western Sambo Ecological Reserve contains the greatest habitat diversity in the Lower Keys.
Significant coral features include spur-and-groove formations, bank reefs, and nearshore patch reefs. A rectangular nine-square nautical mile area, Western Sambo Ecological Reserve begins at the water's edge off the sandy beaches and salt ponds of Boca Chica Naval Air Station. It continues through nearshore hardbottom and inshore patch reefs, out across midchannel reefs in Hawk Channel, over offshore patch reefs and the shallow bank reef, and ends at a depth of 60 feet.
Western Sambo has one of the last remaining stands of living elkhorn coral in the Lower Keys, a species once abundant throughout the Keys. Anemones, crabs, starfish, sea cucumbers, sand dollars, and sea urchins are found nearshore. Surgeonfish, bar jacks, foureye butterflyfish, rosy blennies, neon gobies, grunts, wrasses, angelfish, damselfish, striped parrotfish, butter hamlets, sharpnosed puffers, and schoolmasters are residents at the reef. Huge gray angelfish and hogfish meander the shallow areas of Western Sambo.