We entered the higher temperature zone of the hydrothermal system (about 85 degrees C) today at about 70 m depth. Our day shift drillers, Steve Cole and Beau Marshall, mitigated a serious problem with deterioration of the plastic core liners through increasing the flow of cool, sterilized seawater drilling fluid into the hole. The reservoir of seawater, pumped from the northern peninsula, and the sterilization system, composed of a double filter and two stage UV sterilization components are shown on the right.