 After leaving Nootka Sound, Cook explored and mapped the coast all the way to the Bering Strait, on the way identifying what came to be known as Cook Inlet in Alaska.In a single visit, Cook charted the majority of the North American northwest coastline on world maps for the first time, determined the extent of Alaska, and closed the gaps in Russian (from the west) and Spanish (from the south) exploratory probes of the northern limits of the Pacific.By the second week of August 1778, Cook was through the Bering Strait, sailing into the Chukchi Sea.