The southern tip of Ambergris Caye is the Hol Chan Marine Reserve. Hol Chan is Mayan for 'little channel." This sanctuary was officially established in 1987, and since then the return of all species of fish has been quite dramatic.

Hol Chan Marine Reserve and Shark Ray Alley is approximately 4 miles (6.4 km) south of San Pedro Ambergris Caye. It is the single most popular day trip from San Pedro, perfect for snorkeling or diving. The reserve covers approximately three square miles (7.8 sq km) and is divided into three zones. Each one is clearly marked by buoys. The entire reserve focuses on a cut through the reef which is little more than 25 yards (23 m) wide and 30 feet (9 m) deep.

You must hire a boat and guide out of San Pedro. The costs depend on the services offered. It is easy to mix diving and snorkeling. Trips usually run once in the morning and again in the afternoon.