The world is in the middle of a second gold rush — but it’s not gold they’re mining today. It’s Bitcoin and other cryptocurrencies, ones and zeroes that are being turned into pure profit. Around the globe, they’re making millions from machines, minting with microchips, printing money with printed circuit boards.

These mines aren’t holes in the ground, of course, but rather server rooms where shelves full of highly specialized computers with Application Specific Integrated Circuits (ASICs) work round the clock to mine bitcoin. They do this by solving extremely difficult math problems, and all that work tends to make them get really, really hot. The solution, of course, is to supply them with a steady supply of cold air to prevent them from overheating. Meaning bitcoin mines are very specialized environments with crucial heating and cooling needs, specialized computers, and very unusual environments. We toured one in northern Washington state recently; it was like stepping into a sauna.

But that’s hardly the only Bitcoin mine, nor the weirdest of the bunch. Here we dig in to some of the biggest and most profitable Bitcoin mining farms and pools in the world. (Need a quick refresher before you dive in? Start here.)

Bitmain was founded in 2013 by Jihan Wu and Micree Zhan after the two met following Zhan’s translation of Satoshi Nakamoto’s seminal “Bitcoin White Paper,” a document that spells out the core fundamentals Bitcoin is based upon. Jihan approached Zhan for help in developing a new chip that would be capable of mining Bitcoin, thus Bitmain was created.

Bitmain is also one of the few crypto companies that touts an actual farm, or warehouse full of “mining rigs,” that is maintained by a 24/7 staff of engineers. Having made three to four billion in 2017, they were definitely hauling in their fair share of the catch.

While cryptomining is definitely at the forefront of Bitmain’s business, the company broadened its development projects after its explosive rise in 2017 to include chips and processors that focused on “deep learning” — and in November of that year launched a new line of AI-focused hardware.

Having been around a bit longer than BitMain, Bitfury was founded in 2011 by Valery Vavilov. Unlike BitMain, Bitfury is more in the business of supporting groups who wish to use the Blockchain to move and create assets. So while not necessarily a farm, Bitfury is a leading name in the cryptocurrency world.

With offices across the globe, Bitfury is manned by professionals from all kinds of fields and all kinds of places, all working together to preserve the accessibility and transparency of the Blockchain, as well as creating tools to streamline its use.

In layman’s terms, Bitfury lets big businesses, governments, and other organization transfer assets across the Blockchain. So if you’re a high roller that wants to take advantage of the new cryptocurrency highway, Bitfury may be your first stop.

Opened in May of 2013, DiscusFish is a public mining pool that also shares its origins in China. The name refers to a time before the pool had an English interface; “Discus Fish” is the name of one of their original operators.

F2Pool also supports a wide variety of cryptomining, catering to most of the larger and trending cryptocurrencies in current circulation — Ethereum, Ripple, and so on — as well as a daily automatic pay out.

The second largest public mining pool as of 2012, BTCC has been around just about as long as Bitcoin has. Operating as a “Bitcoin exchange,” the BTCC is arguably one of the largest and more aggressive names in the crypto world.

With a continued faith in Bitcoin that hasn’t failed them yet, the BTCC has successfully ridden the everchanging current that is the crypto world, continuously meeting the demand that the craze currency creates during the “Bitcoin bubble!” phases.

As one of the most open and easy-to-get- into mining pools, Eligius has become a loud name in the Crypto mining world. Operated since 2011, it also boasts being one of the older mining pools.

With a no-nonsense attitude, no registration, no fees, and immediate share-sharing, Eligius is probably the most user friendly you can get with pool mining.