The boiling waters of Doublet Pool quickly cool when reaching the surface and are hence immediately replaced by boiling waters from the depth. This produces impressive audible thumps under the thin mineral crust caused by collapsing gas and steam bubbles. This process causes periodical wave action that builds up the fractal elaborate border ornamentation of the sinter mineral crust. The boiling water dissolves silica from the ryolithic lava bedrock deep underground that precipitates into sinter crusts once the water cooled at the surface. On top of these sinter crust ledges, black and red to brownish bacterial mats feed on iron minerals. The blue of the water documents high temperatures beyond 198°F (92°C). This resembles the boiling temperature of water at the 8000 ft (2440 m) high volcanic plateau of Yellowstone. Only few extreme hyperthermophile microorganisms called archae can survive under such hot conditions. The cold morning air contrasts with the boiling water, resulting in permanent deep fog. Only sporadic wind gusts allow the view on this beautiful pool for few seconds.
Canon 20D, Canon EF-S 10-22mm, f/11, 1 sec, 100 ASA, tripod