Octopus Spring is one of a group of alkaline hotsprings located along a short trail starting from a parking area along Firehole Lake Drive.

The water temperature varies from 95° at the source, to 83° in the outflow channels, and 65° at the distal margin of the microbial mat. The upstream sections of the channels contain microbial "pink filaments." Forming the wide margin, the microbial mat exhibits typical zonation in its vertical structure, illustrated in a picture below. The colors indicate the presence of chlorophylls [green], carotenoids, and pigments [red, orange, yellow] produced by the microrganisms for utilization of sunlight and protection from UV radiation.

The microbial communites of this spring have been extensively studied. Thermus aquaticus, a hyperthermophilic bacteria, was discovered here and has proven to be important to the biotechnology industry as it provides an enzyme needed for the polymerase chain reaction to amplify DNA.