Lake Crescent in Olympic National Park - Washington

First light of day after spending the night in an A-frame cabin on the lake

Before embarking on a kayak trip around the lake

Lake Crescent has the clearest water I've ever seen. Because it is mostly devoid of nitrogen, algae can't grow there and thus it remains extremely clear. This lake is also extremely deep. The story behind it's official and unofficial depths is pretty interesting so I included an excerpt from Wikipedia below:

In the early 1960s, the U.S. Navy did a survey of the lake using a Furuno depth sounder. They were not able to verify the maximum depth on their equipment. During a 1970 depth survey conducted by the students of the fisheries program atPeninsula College in Port Angeles, Washington, students used instruments that could not record measurements beyond a depth of 624 feet, which thus became the "official" depth of the lake as recorded by the National Park Service. However, when power cable was being laid in the lake, instruments showed depths in excess of 1000 feet, the maximum range of the equipment used. The actual maximum depth of Lake Crescent remains unknown.