Kosmos (CAUSE-muss) was an unincorporated community in Lewis County, Washington, southwest of Glenoma and is now considered a flooded town.

[4][5][6] The town's primary economy was based on logging and sawmills, with mining for mercury also a principal venture.

[7] At its most prosperous, Kosmos had a population between 500-600 people, two grocery stores, a post office, and a locomotive shop, among other amenities.

[3][4] Residents relocated from Kosmos, along with its neighboring communities of Neskia and Riffe, in advance of the completion of the Mossyrock Dam in 1968.

Before the Cowlitz River rose behind the dam and formed Riffe Lake, contractors razed most structures, except for their foundations.