Astronauts and caving specialists will soon descend into the depths of the Earth in order to train for future space missions, according to the European Space Agency (ESA).

The 2014 ESA program CAVES - short for Cooperative Adventure for Valuing and Exercising Skills - will begin later this summer under the surface of Sardina, Italy.

This is the fourth CAVES mission to have occurred, with three others having happened in 2011 2012, and 2013. The astronauts will spend a week underground, interacting with one another under the pretence that they are in a real space mission.

Procedures, restrictions, technologies, and even lingo will all reflect that of an actual ESA mission, even while the team hikes, climbs, and rappels deeper and deeper into a natural cave on Earth.

"Caves is an exploration mission," explained CAVES exploration instructor Francesco Sauro in a recent press release, "and this year will be more difficult as the astronauts venture further from basecamp."

It's easy to see how an isolated cave diving mission can be used to measure the behavior and cooperative performance of astronauts who will potentially spend weeks, if not months, together on the International Space Station.

But a deep and dry natural cave is certainly no space-walk. So why caves? NASA similarly has its astronauts prepare for micro-gravity missions by training underwater, but cave diving seems like a stretch.

According to the ESA, there are actually a lot more parralels to be drawn than you'd think.

Like space, cave-diving puts astronauts in low-visibility and high-stress situations with little room for error. If a piece of equipment is dropped in space, it floats away into the endless abyss. If a piece of equipment is dropped while rappelling in a cave, it will drop into steep shadows and cracked earth.

"It will be interesting to see how they manage the further exploration," added Sauro. "As they distance themselves from basecamp it will get more challenging and I am curious to see how far they can go."

You can watch the "debreifing" of last year's expedition below: