northernmost island of Tonga, in the southwestern Pacific Ocean. It is part of the Niuatoputapu, or Niuas, group of islands. The generally wooded land area of 19 square miles (49 square km) includes a volcanic peak 935 feet (285 metres) high, several lakes—including a large crater lake (Vai Lahi, containing several islands, one of which contains a crater lake of its own)—and numerous hot springs. During a particularly violent eruption in 1946, the island's inhabitants, numbering some 1,200, were evacuated to Euaʿ Island, several hundred miles to the south. They began returning to Niuafoʿou in 1958. Because of an unusual method of receiving its mail in cans dropped from passing ships, Niuafoʿou gained the nickname Tin Can Island.