Guichen Bay, (French: Baie de Guichen) is a bay located on the south-east coast of the Australian state of South Australia about 115 kilometres (71 miles) northwest of the regional city of Mount Gambier and about 270 kilometres (170 miles) south-southeast of the state capital of Adelaide. It was named in 1802 by the Baudin expedition of 1800-03 after Luc Urbain de Bouëxic, comte de Guichen. The town of Robe is located at the southern end of the bay.