Protector Shoal is a submarine volcano, also called seamount, which rises gently from an ocean depth of 3,900 feet (1,200 m) to about 55 metres (180 ft) below sea level approximately 31 miles (50 km) NW of Zavodovski Island in the South Sandwich Islands chain. The last eruption occurred during March 1962. Protector Shoal is the only volcano in the arc that has erupted rhyolite pumice.