Online Tours Congress Pool A visit most times of the year will show a Congress Pool that appears pale blue in color as picture on the left. Due to the variable nature of Norris features it is possible to see the same pool looking muddy and boiling violently as pictured below. No other thermal area in Yellowstone exhibits this phenomenon. Mysteriously features throughout the Norris area undergo dramatic behavioral changes literally overnight.
Clear pools become muddy and boil violently, and some temporarily become geysers.
Features that typically behave as geysers may display altered eruption cycles or temporarily cease erupting. New features may be created during a disturbance, although they seldom remain long-term attractions at the basin. Disturbances tend to last from a few days to more than a week. Why this happens is not fully understood. Further study will no doubt yield new clues that will help unravel the mystery of this phenomenon and lead to a greater understanding of the earth's hidden geologic forces.