At an elevation of 5414ft on the very crest of the Cascades, Waldo Lake has no stream inlets – the only water that enters is snowmelt and rainfall. It is one of the purest bodies of water in the world and is the source of the Willamette River. The lake is amazingly transparent – objects 100ft below the surface are visible.
Not only is it Oregon's second-deepest lake (420ft), it's also the state's second-largest lake (10 sq miles). The west and north sides of the lake are contained in the Waldo Lake Wilderness Area, a 148-sq-mile area that abuts the Three Sisters Wilderness and is filled with tiny glacial lakes, meadows and hiking trails. No motorized gas boats are allowed, but afternoon winds make the lake popular for sailing. Three lovely USFS campgrounds flank the eastern half of the lake.