With over 10 weeks of training under your belt, a successful Hell Week, and the transition to “Dive Phase,” every candidate is feeling pretty good about things at this point. That is, until the first day of Second Phase.

The first evolution of Second Phase is a conditioning drill that catches just about everybody off guard. The only true way to describe it is that you get your ass handed to you as the instructors remind you that you still have a long way to go. “The only easy day was yesterday.”

For the rest of the phase, assuming nobody messes up, you spend the bulk of your time in dive classes and underwater, breathing pure oxygen from what’s called a “Rebreather.” The final hurdle in second phase is called “pool comp.” It is here that the instructors rip your regulator out of your mouth, tie your hoses in knots, and spin you around until near-drowning occurs.

If you’re not comfortable in the water, this will either fix that forever or terrify you for the rest of your life.