Coos Bay is a city located in Coos County, Oregon, United States, where the Coos River enters Coos Bay on the Pacific Ocean. The city borders the city of North Bend, and together they are often referred to as one entity called either Coos Bay-North Bend or the Bay Area. Coos Bay's population as of the 2010 census was 15,967 residents, making it the largest city on the Oregon Coast.