Thanks to a Google Earth update containing two decades of data from seafloor-scanning expeditions, armchair explorers can take a virtual submarine ride into Earth’s last frontier.

Oceanographers say that more is known about the surface of Mars than the deep seafloor of Earth. They’re right: Only a fraction of our seafloors have been studied. But with oceans covering 70 percent of Earth’s surface, a fraction is still quite a lot. The latest update, released on World Oceans Day, covers an area the size of North America.

Assembled by Columbia’s Lamont-Doherty Earth Observatory, the data comes from some 500 expeditions run by 12 different institutions. It’s state of the art, but it can also be hard to navigate at first. Below is a quick walk through to get you started. If you find an interesting spot, be sure to drop a pin and let us know in the comments.

1. You’ll want to download two layers of map data: the Global Multi-Resolution Tomography cruise tracks (.kmz) and the Seafloor Update (.kmz). Once they’re installed, you’ll see a tracery of multicolor lines representing the voyages of seafloor-scanning ships. In this screenshot, Google Earth is targeted off the west coast of Central America.

2. After zooming to an altitude that balances large-scale features with a bit of detail, scan for places of interest. Where many lines intersect, the undersea picture should be especially clear (and there may be a reason for all those lines).

3. The ship’s lines can get cluttering, so you can turn them off as you approach an interesting place.

4. Zoom in….

5. Drag-and-drop the Street View icon (a little orange man above your zoom scroller) to a point where you’d like to stand.

6. Voila! You’ll be deposited on the bottom of the ocean, free to explore (and minus the thousands of pounds per square inch of pressure).

Images: Google Earth

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