Recently, I fished Lost Lake in the Cajon Pass, near Highway 215 in California. This little sag lake, in a fault line, is very, very deep. It is spring fed and has crystal clear water.
Video
The fish were very wary and shoreline access was limited. However, between my friend and I, we managed to land 3 largemouth and one bluegill. It's a very odd lake that feels out of place amidst the dry scrub brush and nettles.
Be nice.