an open gulf in the Pacific Ocean between the Alaskan Peninsula and the North American mainland. The Gulf of Alaska is more than 2,200 km wide at its mouth and reaches a depth of 5,659 m. The archipelagoes of Kodiak, Alexander, and the Queen Charlotte Islands are located in the Gulf of Alaska. Tides are semidiurnal, reaching 12 m, and mixed, reaching 6.8 m. The chief ports are Seward in Alaska and Prince Rupert in Canada. The Russian geographer F. P. Litke established the first marine observatory in the Pacific Ocean in 1840 on Baranof Island in the Gulf of Alaska. There is a fishing industry.