Bitcoin mining was once feasible at home using GPU power but that’s no longer true. As the price of the virtual currency skyrocketed over the course of 2013, entrepreneurs like 31-year-old Emmanuel Abiodun began investing serious money in Bitcoin-specific mining hardware that effectively put GPU mining out to pasture.

While most serious Bitcoin miners elect to keep their setups private, Abiodun recently opened the doors to his massive mining facility in Iceland to journalist Nathaniel Popper. Behind the fortified gate and multiple security checkpoints lie more than 100 mining computers, each locked away inside a metal cabinet cooled by vents on the floor.

The machines, which require a massive amount of energy and produce excessive amounts of heat, are cooled primarily by the crisp Arctic air that is pumped in from outside. Abiodun, who runs a mining rental service known as Cloud Hashing, chose Iceland for the installation due to the cheap hydroelectric and geothermal energy sources.

The machines mine away on the Bitcoin network 24/7. At the end of each day, the mining haul is divided up and sent to the company’s customers. For example, the operation mined 225 Bitcoins one day last week which were valued around $160,000. The company said they keep about 20 percent of the capacity for their own use and rent out the remaining space.

Since October, the hardware has generated more than $4 million worth of Bitcoins based on current trading value. At that rate, Abiodun is set to make a hefty profit in no time flat should the crypto currency continue its meteoric rise.