Observatory Inlet is an inlet on the North Coast of British Columbia. It is a northward extension of Portland Inlet, other sidewaters of which include the Portland Canal. The entrance of Observatory Inlet, from Portland Inlet, lies between Ramsden Point and Nass Point. Ramsden Point also marks, to the west, the entrance of Portland Canal. Observatory Inlet was named by George Vancouver in 1793, because he set up his observatory on the shore of the inlet, at Salmon Cove, in order to calibrate his chronometers. His two vessels, HMS Discovery and HMS Chatham, stayed in Salmon Cove from July 23 to August 17, 1793. During this time a boat surveying expedition under Vancouver himself explored Behm Canal. Vancouver also named three headlands at the entrance of Observatory Inlet: Maskelyne Point, for Nevil Maskelyne, the Astronomer Royal, Wales Point, for William Wales, the mathematical master who sailed with James Cook, and Ramsden Point, after the famed mathematical instrument-maker Jesse Ramsden.