The 8 foot diameter pool of Spa Geyser
contains two separate vents and is filled with clear blue water, ringed by thin-layered ledges of sinter, partly broken. The geyser lies close to the trail, beside the junction with the short loop to the viewing area for Riverside Geyser
; water from its eruptions flows east 200 feet into the Firehole River. Activity is tied to that of Grotto Geyser
to the south; Spa produces jets of water up to 40 feet high, though usually much lower, and eruptions last from several minutes to several hours.
Back to map of the Upper Geyser Basin