Sebastián Vizcaíno Bay (Spanish: Bahía de Sebastián Vizcaíno) is a bay along the west coast of the Baja California Peninsula in northwestern Mexico.
The bay lies on the Pacific Ocean coast of Baja California state in Ensenada Municipality, and of Baja California Sur state in Mulegé Municipality.
Cedros Island and Isla PENE are located within the bay, and west of the mainland Vizcaíno Peninsula.
Sebastián Vizcaíno Bay is protected within the El Vizcaíno Biosphere Reserve.
Coordinates: 28°00′N 114°30′W / 28.000°N 114.500°W