Midway Geyser Basin
Midway Geyser Basin, as its name suggests, is located between the Upper and Lower Geyser Basins. To reach it, drive 5.9 miles north of the Old Faithful Interchange, or 10.2 miles south of Madison Junction on the Old Faithful to Madison section of the Grand Loop Road. The number of features here are less than the other basins, but they are some of the largest and most interesting in the park.
The pathway leaves the parking area and immediately crosses the Firehole River on a large wooden bridge. Thermal runoff from Midway Geyser Basin pours into the river down a sharp incline to the left.
Excelsior Geyser Crater
The boardwalk climbs briefly up towards a feature who’s size is clear long before it is seen from the massive amounts of steam rolling off it. The boardwalk levels off, exposing the massive Excelsior Geyser Crater. This geyser blew itself apart in a massive explosion, leaving this relatively calm, but enormous pool.
Grand Prismatic Spring
The most well-known feature of the area is Grand Prismatic Spring. This massive pool is the largest in the park. The best views of it are from the recently constructed overlook trail. As seen to the left, it is impossible to appreciate from closer up.
Two other notable pools are in the Midway Geyser Basin. The first is Turquoise Pool.
The second is Opal Pool, a beautiful green-blue pool set in a massive area of travertine buildup.