McArthur-Burney Falls [EXPLORED]
Lovely, magical, 129 foot waterfall between Mt. Shasta and Mt. Lassen. The water comes from underground springs, both filling the river above the falls and directly through the porous basalt cliff face itself, flowing out at a rate of 100 million gallons a day. The ambient temperature above the falls was about 105, but in the basin below the air temperature dropped to a chilly, enlivening 50 degrees. I spent four hours or so down there, and continued to hear the falls while driving away and for the rest of the night.