Madison Yellowstone is an area where two rivers join: the Firehole River and the Gibbon River. Known as Madison Junction, there is a historic log cabin here that functions as a visitors’ center with historical exhibits and information about the surrounding area. From Madison Yellowstone, you can explore some of Yellowstone's famous waterfalls, such as the Firehole Cascades and Falls near Firehole Canyon, and Gibbon Falls north of the Junction. Madison Campground is a good place to stay if you are spending a few days exploring the surrounding geological features.
The Firehole River flows from Madison Lake down through the mountains to join the Gibbon River at Madison Junction. During its journey, the cold mountain water is warmed by hot water running off from hot springs and geysers. One of the most visually distinctive examples of this steaming hot runoff is at Excelsior Geyser, where a sheet of 200-degree Fahrenheit water runs over a bed of rock into the Firehole River. Firehole River is a haven for rainbow trout, and fly fishing is permitted.
Just a few miles north of the river junction at Madison Yellowstone is the two-mile long Firehole Canyon, where the river flows over Firehole Cascades and Firehole Falls. You can access this canyon by the one-way Firehole Canyon Road, which parallels the Canyon. Located between the dangerous Firehole Cascades and the 40-foot Firehole Falls is one of the hidden gems of Yellowstone National Park, the Firehole swimming hole.
One of only two places in the park that you are legally permitted to swim, the swimming hole is a calm pool of water warmed by geothermal runoff, but cooled by cold mountain water, making it an acceptable temperature for swimming. It is only open during the summer months, and can be accessed by a turnoff from the Firehole Canyon Road. Some visitors like to walk upstream a little bit, and let the flowing water push them as they bodysurf down to the swimming hole. Keep in mind that there are no lifeguards at the swimming hole, so be very careful when swimming, and keep a close watch on children.
Soon after the Firehole River exits Firehole Canyon, it joins the Gibbon River at Madison Yellowstone. Upstream of Madison Junction on the Gibbon River, you can view the beautiful Gibbon Falls, with a viewpoint accessible by car on the Grand Loop Road. The 84-foot-high Gibbon Falls fans out in a foaming sheet of white water before plunging into the Gibbon River below.
You may also want to visit the little-known Monument Geyser Basin near the Gibbon River. There are several fumaroles and hot pools in the area, and the most distinctive geothermal feature here is Monument Geyser, a tall cone geyser that is eight feet tall and only two feet wide. It is surrounded by several smaller cone geysers that are mostly dormant. The Monument Geyser Basin is located south of Gibbon Meadows and can be reached by a one-mile trail—it’s a short hike, but it’s also over quite steep and challenging terrain.