Old Faithful Geyser
Between 1983 and 1994, four probes containing temperature and pressure measurement devices and video equipment were lowered into Old Faithful. The probes were lowered as deep as 72 feet (22 m). Temperature measurements of the water at this depth was 244 °F (118 °C), the same as was measured in 1942. The video probes were lowered to a maximum depth of 42 feet (13 m) to observe the conduit formation and the processes that took place in the conduit. Some of the processes observed include fog formation from the interaction of cool air from above mixing with heated air from below, the recharge processes of water entering into the conduit and expanding from below, and entry of superheated steam measuring as high as 265 °F (129 °C) into the conduit.