You spend most of your time in Rapture — BioShock’s failed underwater utopia – dodging splicers, firing rockets at Big Daddies, and listening to rants of Randian philosophy. There isn’t time to admire the architecture, or wonder how it got there in the first place.

Andrew David Thaler is a deep-sea biologist with that kind of time. Over at Southern Fried Science, a blog written by marine scientists of various backgrounds, Thaler dove deep into the elements of the seminal FPS to figure how Rapture runs, and just where under the sea it would be.

Under the Sea…

First, Thaler wanted to pinpoint Rapture geographically. Looking at a number of the names of Rapture locations, as well as a set of coordinates the player glimpses in a flashback, Thaler concludes that the city is somewhere under the northern mid-Atlantic ocean.

But Rapture can’t just be anywhere. The deep-sea is an inhospitable place. There is no light, little heat (just a few meters under the surface the oceans rapidly cools to around 4 degrees Celsius), and crushing pressures.

Looking to the underwater environments we have constructed, Rapture itself probably isn’t pressurized to anything more than normal atmospheric pressure. If the city were too deep, the air pressure inside the buildings would be so high to prevent collapse that it would induce oxygen poisoning in its inhabitants. At a deep depth, Thaler notes, “Oxygen becomes toxic and nitrogen induces a drug-like state, appropriately dubbed by early divers ‘the rapture of the deep.’”

Oh, and since Rapture isn’t “continuously flooded with perpetually burning walls of flame,” that’s another reason to think Rapture doesn’t use equal pressure to support its structures. More likely, Rapture is built with massive steel walls and exists a few hundred meters or less below the northern mid-Atlantic.

More clues to Rapture’s location are the animal and plant life. The humpback whales, colossal squid, and seaweed suggest that Rapture is much closer to the surface than it looks.

…Somewhere

Then there is the question of livability. Thaler writes that any underwater civilization will need oxygen, heat, and power. “Fortunately, there’s a source for all of those things right near the coordinates revealed in the game.” That’s the mid-Atlantic ridge, a giant crack in the Earth’s crust that spews out enough geothermal energy to power most of modern-day Iceland.

Walking through Rapture with shotgun in hand, you’ll see hydrothermal vents that lack the deep-sea fauna that indicate depth. These vents must be shallow, as must Rapture. And in BioShock 2, a villain speaks of casting a part of Rapture into a “trench,” again indicating a shallow location on the mid-Atlantic ridge.

Putting all the lines of evidence together, Thaler gives Rapture a location. “Based on its geologic setting, the limitations of human engineering, and the marine species found swimming and crawling around the city, the base of Rapture is no more than 150 meters from the surface.”

And if that weren’t enough, Thaler looked at the suits of the game’s Big Daddies to give another indication of depth. Given the state of diving technology around the 1940s and 50s, and the appearance of the suits themselves, Rapture again lies not much deeper than 100 meters under an oddly-placed lighthouse.

“In the end, it turns out that Rapture, like Andrew Ryan and the objectivist philosophy that inspired his utopia, though grand in vision, is ultimately much shallower than it first appears.”

Read the whole nerdy analysis, which is worth a read for its thoroughness, over at Southern Fried Science.

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IMAGES: Irrational Games; 2K Games