How do you map the ocean floor? - in 15 secs

In a bid to map striking areas of the ocean floor and make them "walkable" on its Street View service Google has sent divers to the island of Fernando de Noronha.

It was their first stop in Brazil, but they also plan to map the country's other national marine parks.

Google has already mapped Australia's Great Barrier Reef, the Galapagos islands and other areas of the ocean floor.

But how do they do it?

Video courtesy of Google and produced by BBC Brazil's Paula Adamo Idoeta.