Lake Coeur d'Alene, officially Coeur d'Alene Lake, is a natural dam-controlled lake in North Idaho, located in the Pacific Northwest region of the United States. At its northern end is the city of Coeur d'Alene. It spans 25 miles (40 km) in length and ranges from 1 to 3 miles (5 km) wide with over 109 miles (175 km) of shoreline.

Coeur d'Alene is a city and the county seat of Kootenai County, Idaho, United States. It is the most populous city in North Idaho and the principal city of the Coeur d'Alene Metropolitan Statistical Area. The population was 54,628 at the 2020 census. Coeur d'Alene is a satellite city of Spokane, which is located about thirty miles (50 km) to the west in the state of Washington. The two cities are the key components of the Spokane–Coeur d'Alene Combined Statistical Area, of which Coeur d'Alene is the third-largest city. The city is situated on the north shore of the 25-mile (40 km) long Lake Coeur d'Alene and to the west of the Coeur d'Alene Mountains. Locally, Coeur d'Alene is known as the "Lake City," or simply called by its initials, "CDA."