Riverside Geyser has one of the most picturesque settings of any geyser.
Riverside is a cone-type geyser. Its interval is usually 5 1/2 to 7
hours, its height about 75 feet and its duration about 1/2 hour. The
water phase of the eruption lasts about 20 minutes and is followed by a
You watch Riverside from a viewing area across the Firehole river
from the geyser. From this position, Riverside's formation looks
something like a chair. There is a vent high up on the back and another
vent in the seat of the chair. Except for some minor splashing, the
geyser erupts from the lower vent in the seat of the chair. About 1 1/2
to 2 hours before the eruption the main vent in the seat of the chair
begins to overflow into the river. This overflow is variable. About an
hour later, the small vents behind the main vent will begin to bubble
and boil. The activity fluctuates but seems to build as time progresses.
Finally a splash or two will be seen in the upper vent at the top of the
chair back. One of these splashes will be large enough to spill water
into the river, this usually starts the eruption.