USS Block Island (CVE-21/AVG-21/ACV-21) was a Bogue-class escort carrier for the United States Navy during World War II.

Block Island had capacity for up to 24 fighter and anti-submarine aircraft normally a mixture of Grumman Wildcat and Avengers with composition dependent upon the mission.

Departing San Diego, California in May 1943, Block Island steamed to Norfolk, Virginia, to join the Atlantic Fleet.

She then made two trips from New York City to Belfast, Northern Ireland, carrying Republic P-47 Thunderbolt fighters.

On 28 October 1943, her Avenger and Wildcat aircraft sank U-220 with depth charges at 48°53′N 33°30′W / 48.883°N 33.500°W / 48.883; -33.500 (German submarine U-220), fifty-six men were killed (all hands).

[1] Eugene E. Elmore attacked and sank U-549 using her hedgehog spigot mortar system and depth charges in 31°13′N 23°03′W / 31.217°N 23.050°W / 31.217; -23.050 (German submarine U-549).