This location is awfully close to one of the spots Plato, Legendary Smart Dude, had pinpointed as a possible resting place of Atlantis. In addition, the site is about the same size as Plato described.
Google claims that the lines are remnants of the sonar traces left by boats as they surveyed the area. Plus, Plato described Atlantis as being designed as a series of concentric circles, not a grid.
Now I hate to call Google a bunch of dirty liars, but that is clearly Atlantis. Haven't you ever heard that circles look square when viewed underwater? Yeah, it's called refraction. It's the same principal that makes a toot smell worse if you do it in the bathtub. Science, folks, you can't argue with that.
*Stop emailing me, I'm fully aware Africa is a continent.