The activity only lasted a few days. For years, Spouter Geyser was in eruption about two thirds of the time with durations of several hours and quiet periods of only an hour or two. In recent years, this has changed. In 1997, Spouter was in eruption only about one quarter of the time with durations lasting from one half to two hours. Spouter has splashing eruptions to about 6 feet.
Sunset Lake is the largest hot pool at Biscuit Basin.
Unfortunately, its high temperature often creates large steam clouds that obscure the pool. During much of the time, Sunset Lake periodically boils up at the center of the pool to two to ten feet. More unusual are actual eruptions, most recently seen in late 1995 and 1996. These eruptions consist of very heavy boiling and bursting at the center of the pool that can reach 20-35 feet. Whistle is a very rare geyser with decades passing between seen eruptions.