Herbert Island is an island in the Islands of Four Mountains subgroup of the Aleutian archipelago. It is 3.1mi from Chuginadak Island, separated by the Chuginadak Pass. Yunaska Island is 16mi southeast of Herbert Island. Measuring 6.2mi across, Herbert Island is somewhat circular in shape and is covered by the 4,200ft Herbert Volcano, whose two km wide caldera is one of the largest in the Aleutian Islands. There have been no recorded eruptions here. The island is 8.95km long and 9.14km wide.