Piner Bay is an open bay 15 kilometres (8 nmi) long and 3.7 kilometres (2 nmi) wide between Cape Bienvenue and the east side of Astrolabe Glacier Tongue. Discovered on January 30, 1840, by the United States Exploring Expedition under Wilkes, who named it for Thomas Piner, signal quartermaster on the USEE flagship Vincennes.