10.5 mi. N of Baranof, on NE coast of Baranof I., Alex. Arch. 0.3 mile wide.
Named in 1895 by Lieutenant Commander E. K. Moore, U.S. Navy (USN), for the steam launch Cosmos of the U.S. Coast and Geodetic Survey (USC&GS) steamer Patterson, which aided in the exploration of this region.
The Basin, Cosmos Cove, Echo Cove, Ell Cove, Hanus Bay, Kasnyku Bay, Kelp Bay, Lindenberg Harbor, Middle Arm Kelp Bay, South Arm Kelp Bay, Takatz Bay, Warm Spring Bay, Warm Springs Bay, Waterfall Cove,
Catherine Island, Crow Island, Dead Tree Island, Fairway Island, McClellan Rock, O-Neil Island, Pond Island, Reshimosti Island, Round Island, Svensen Rock, Takatz Islands, Traders Island, White Rock, Yellow Rock, Zubof Rock,