The Quimper Peninsula is a narrow peninsula forming the most northeastern extent of the Olympic Peninsula of Washington state in the northwestern United States of America.
The peninsula is named after the Peruvian-born Spanish explorer Manuel Quimper who, in command of the Princesa Real, charted the north and south coasts of the Strait of Juan de Fuca during the summer of 1790. The Spanish had given the name Quimper to today's New Dungeness Bay, which George Vancouver had renamed New Dungeness. In 1838 Charles Wilkes gave the peninsula the name Dickerson, but the U.S. Coast Survey renamed it with Quimper's name.
The Quimper Peninsula is defined by Discovery Bay to the west, the Strait of Juan de Fuca to the north, and Port Townsend Bay to the east. From the isthmus it extends approximately seven miles to the north-northwest and then curves to the northeast for another four miles before terminating at Point Wilson. For most of its length the width is less than four miles. This peninsula forms the westernmost boundary of Admiralty Inlet. Its approximate geographic center is at coordinates 48°5′N 122°50′W / 48.083°N 122.833°W.