The bottom of the world’s oceans is one of the last unexplored frontiers remaining on Earth. What hides in the deepest depths? A lot, it turns out, according to new research by a team from the University of California, San Diego. Using previously untapped streams of satellite data, they’ve mapped the ocean floor with unprecedented detail.

The new map is twice as accurate as its predecessor, which was produced some 20 years ago. Particularly improved are the topographical features of the most remote reaches of the seafloor.

“The kinds of things you can see very clearly now are abyssal hills, which are the most common land form on the planet,” said David Sandwell, lead scientist of the paper and a geophysics professor in the Cecil H. and Ida M. Green Institute of Geophysics and Planetary Physics (IGPP) at Scripps.

The map was created by combining data from the European Space Agency’s (ESA) CryoSat-2 satellite, which primarily captures polar ice data but also operates continuously over the oceans, and Jason-1, NASA’s satellite that was redirected to map the gravity field during the last year of its 12-year mission.

The map not only reveals unseen features like continental connections and seafloor spreading ridges, but also improves depth estimates in 80% of the ocean. Much of that terrain is buried beneath as much as a mile’s worth of sediment, if it’s been charted at all. The map also forms the foundation for Google’s upcoming ocean maps.

“The team has developed and proved a powerful new tool for high-resolution exploration of regional seafloor structure and geophysical processes,” says Don Rice, program director in the National Science Foundation’s (NSF) Division of Ocean Sciences. “This capability will allow us to revisit unsolved questions and to pinpoint where to focus future exploratory work.”

To check out the full suite of maps, which include kilometer-high mountains, head over to UCSD’s Marine Gravity homepage.