Encircling Blue Lagoon’s Visitor Centre is a surreal pool. The blue color and white mud are evidence of silica. During evaporation, the rich minerals convert to white clay while clinging as residue to the rocks. This is part of the Illahraun lava field, produced by a violent volcano in 1226. Deep below the surface is the Svartsengi Geothermal Field. Its name means Black Meadow.