NASA is testing a new submarine that will hunt for undiscovered sea life — and scientists eventually want it to look for aliens on Europa

Diving to the bottom of the ocean is arguably harder than rocketing into space.

Hundreds of astronauts have left Earth, but you can count the people who’ve visited the very bottom of the ocean on one hand: James Cameron, Jacques Piccard, and Don Walsh.

Because of that, we don’t know much about what goes on in the deepest parts of the ocean, especially in the hellishly named hadal zone that’s 6,000 to 11,000 meters (3.7-6.8 miles) under the surface. Although the deepest 45% of the world’s oceans exist in that zone, that part of the planet has been a mystery to us land dwellers.

Until now.