Ask a SEAL what that’s like, and they’ll say it’s like being locked in a cold, dark, wet closet for hours.

“Ever take an ice bath?” said a SEAL who spoke to The Hill on the condition of anonymity. “It’s a tall order.”

After they reach their target and conduct their mission, SEALs have to make it back home, often the same way they came.

The new vehicles, which are called dry combat submersibles, will be akin to mini-submarines, and allow SEALs to stay warmer and drier for longer, and more physically ready, as they close in on their target.

That’s a huge advantage for missions that one retired SEAL who is now a congressman described as “can’t fail.”

“These are national command authority missions. Can’t fail. So in those niche missions, it’s really important we have technology that’s cutting edge,” said retired Navy SEAL Commander Ryan Zinke (R-Mont.).

The vehicles will also allow the SEALs to communicate before a mission, compared with “only seeing your buddy’s eyes” and a glow stick for 10 hours, the SEAL joked.

The first submersible is due to arrive in July 2018, and it will be operational as early as the fall. Final testing is to be completed in 2019.