Mischief Reef is located at latitude 9 degrees 55 minutes east longitude 115 degrees 32 minutes, the Mischief Reef is an atoll, about nine kilometers from east to west, 5.2 km wide from north to south. Mischief Reef in the middle of the lagoon, the depth of about 25.6 m. Four weeks reef 6 feet above water at low tide. 3 imports to enter the lagoon. All three entrances in the south and southwest, the large vessels at high tide through one of the largest in southern entrance into the lagoon. Southwest gate width 92 m, 414 m long, 23.8 m deep waterways, water crossing is a little reef development and hinder the fairway. The south gate a little reef distribution waterway divided into two parts, East Road, a narrow 18 m water depth of 1.8 m; West Road, 37 meters wide, 275 m long, 18 meters of water depth above. Waterway when the flow rate of 1.3 in the neap tide. Atoll northeast of relatively shallow depth of only 1.8 m of the reef head distribution.