From the Sandwich Islands Cook sailed north and then north-east to explore the west coast of North America north of the Spanish settlements in Alta California. 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 north-west 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.