By immersing IT equipment in liquid coolant, a new data center is reaching extreme power densities of 250 kW per enclosure. At 40 megawatts, the data center is also taking immersion cooling to an entirely new scale, building on a much smallerproof-of-concept from a Hong Kong skyscraper. The facility is being built by Bitcoin specialist BitFury and reflects how the harsh economics of industrial mining have prompted cryptocurrency firms to focus on data center design to cut costs and boost power. But this type of radical energy efficiency may soon be key to America's effort to build an exascale computer and the increasingly extreme data-crunching requirements for cloud and analytics.