Castle Geysir by Marcel Zaugg
The Scotsman who was living on my couch last year had come from (and returned to) working on a farm in Iceland right next to Geysir, the original geyser from which the name comes. He said that over the ages the mouth has built up high enough with mineral deposits that the pressure no longer rises enough for the water column to clear the lip and naturally erupt that spectacularly anymore. They used to pour detergent into it to make it blow but environmentalists complained about them effectively just dumping industrial chemicals into nature on the reg, so now they only do it on special occasions.
