Midway Islands, discovered in 1859 by the N.C. Middlebrooks, is a 6.2 km² atoll located in the North Pacific Ocean. It is less than 140 nautical miles east of the International Date Line, about 2,800 nautical miles (5,200 km) west of San Francisco and 2,200 nautical miles (4,100 km) east of Tokyo. It consists of a ring-shaped barrier reef and several sand islets.