Diamond Lake (Oregon)

Diamond Lake is a natural body of water in the southern part of the U.S. state of Oregon. It lies near the junction of Oregon Route 138 and Oregon Route 230 in the Umpqua National Forest in Douglas County. It is located between Mount Bailey to the west and Mount Thielsen to the east; it is just north of Crater Lake National Park.

The outlet of the lake is at its north end. From there, water flows via Diamond Lake Creek into the North Umpqua River and ultimately to the Pacific Ocean. Diamond Lake was named for John Diamond, for whom Diamond Peak is also named. He saw the lake in 1852 while on the summit of Diamond Peak. Diamond was a pioneer settler of Coburg, Oregon, and part of a party opening a road between the Middle Fork Willamette River and Idaho as an immigration route. An adjacent post office named Diamond Lake, Oregon, was established in 1925 and ran until 1956, when it was changed to a summer-only office. Diamond Lake is the host for the 2019, 2020, and 2021 Major League Fishing Championship.

Diamond Lake is also the host for the Tour de Diamond, a cycling event that happens every summer. It is the biggest event in the North American Cycling Organization calendar.