Diablo Lake is a reservoir in the North Cascade mountains of northern Washington state, created by Diablo Dam. There are boat tours and camp grounds available. The dam is part of the Seattle City Light Skagit River Hydroelectric Project. The unique, intense turquoise hue of the lake's water is attributed to the surrounding glaciers that grind rocks into a fine powder that is carried into the lake through creeks. That fine powder stays suspended in the lake, giving the water its brilliant color. This glacier system is the largest in lower 48 states.