Biscuit Basin

Biscuit Basin is accessible right off of the main park road, just a couple of miles from the main Upper Geyser area. You could walk to it from the Upper Geyser area if you continue along the path that leads to Morning Glory Pool. We didn't take that path, but drove to the parking lot. The best feature at Biscuit Basin is the Sapphire Pool. It is beautiful hot blue lake. The bluer the water, the hotter the lake. The colors in the Yellowstone lakes are caused by heat tolerant algae and bacteria, they can thrive in water temperatures that would kill ordinary plant life. But if the water is too hot, such as at Sapphire Pool, even the heat tolerant plants can not survive, and so the water looks pure blue.

There is a trailhead from Biscuit Basin that leads to Mystic Falls. Mystic Falls tumbles down over the edge of the rim of the Yellowstone Caldera. (Biscuit Basin, and most of the park, is on the floor of the crater of a giant volcano that erupted hundreds of thousand of years ago.) The trail splits, you can to the top of the falls or the bottom. We took the low trail and looked up at the falls. There is still a good amount of water flowing, despite the fact that we visited at the end of summer, which is presumably the driest season. You can see steam rising from a vent at the bottom of the falls, water must seep into the crust and get superheated by the magma just below the surface.