Avacha Bay (Russian: Авачинская губа, Авачинская бухта) is a Pacific Ocean bay on the southeastern coast of the Kamchatka Peninsula. It is 24 km (15 mi) long and 3 km (2 mi) wide (at the mouth), with a maximum depth of 26 m (85 ft).[1]

The Avacha River flows into the bay. The port city of Petropavlovsk-Kamchatsky and the closed town of Vilyuchinsk lie on the coast of the bay. It is the main transport gateway to Kamchatka region. The bay freezes in the winter.

It was first discovered by Vitus Bering in 1729. It was surveyed and mapped by Captain Mikhail Tebenkov of the Imperial Russian Navy in the 1830s.[2]

NOTE: Avacha Bay (Avachinskaya Guba) should not be confused with Avacha Gulf (Avachinskiy Zaliv), which lies off the Pacific Ocean outside Avacha Bay.