Bahía Magdalena (Magdalena Bay) is a 50 km long bay in Comondú Municipality along the western coast of the Mexican state of Baja California Sur. It is protected from the Pacific Ocean by the sandy barrier islands of Isla Magdalena and Isla Santa Margarita.
This bay is particularly noted for the seasonal migration of the California Gray Whales that come here during winter to mate. The bay is also popular for commercial and sports fishing. Nearby mangrove swamps provide sanctuaries for sea birds. The bay includes the small fishing port of San Carlos, as well as Puerto López Mateos, which provides a good place to observe the whales.
In 1908, an American fleet of sixteen battleships on a cruise around the world, the Great White Fleet, stopped in the Bay and carried out gunnery practice.
In 1912, Japan tried to purchase the harbor from Mexico. Barbara Tuchman's book The Zimmerman Telegram mentions both the German kaiser as well as the Japanese Emperor attempting to utilize this and perhaps Whale Bay for military naval purposes pre-World War I.