Riverside Geyser was named by members of the 1871 Hayden Survey for its location next to the Firehole River. The geyser has a fairly regular eruption cycle--about every seven hours and lasts about 20 minutes. Water sprays from the geyser only during the early phase of eruption. The geyser erupts at an angle (about 70 degrees) and sprays water and steam over the river.