After 36 days of battling sharks that kept biting their equipment, scientists have returned from the remote Pacific Ocean with a new way of looking at the world’s largest—and possibly most mysterious—volcano, Tamu Massif.

The team has begun making 3-D maps that offer the clearest look yet at the underwater mountain, which covers an area the size of New Mexico. In the coming months, the maps will be refined and the data analyzed, with the ultimate goal of figuring out how the mountain was formed.

It's possible that the western edge of Tamu Massif is actually a separate mountain that formed at a different time, says William Sager, a geologist at the University of Houston who led the expedition. That