This short ½-mile boardwalk trail will guide you through the Yellowstone hydrothermal areas that include Jewel Geyser, Mustard Spring, Black Opal Pool, and more. Biscuit Basin, because of its unusual biscuit-like deposits, was named the same, but during the 1959 Hebgen Lake Earthquake, Sapphire Pool erupted and blew the biscuits away! But even minus the biscuit deposits, Sapphire Pool is still impressive and you'll marvel at the bubbling and steaming springs surrounded by mellow, reflective pools that send rippling runoff over vibrant orange bacterial mats. If you like hiking, take the 2/3-mile lollipop-loop extension off the Biscuit Basin Loop and head towards Mystic Falls, Observation Point, Summit Lake, and Fairy Creek Trail. It's an easy walk from the boardwalk to the parking lot and it's pretty flat once you pass the small hill at the beginning of the hike. Bring sunscreen and sunglasses as this thermal area does get hot! To reach the trailhead, from Old Faithful, drive 2.5 miles north on Grand Loop Road (Route 89) and turn left (west) into the parking area for Biscuit Basin. Otherwise, drive 14 miles south of Madison Junction on Grand Loop Road to reach the trailhead. Biscuit Basin is 3.5 miles south of the trailhead for Midway Geyser Basin and 5.5 miles south of the trailhead for Fountain Paint Pot Trail.