Perisher is the course that those who have been selected as potential Submarine Captain material have to pass.

It’s a very harsh test where prospective Captains are put through increasingly-pressured situations to see if they can cope. Teacher (as they’re called) is responsible for controlling the surface ships, helicopters and anti-submarine measures to test the mettle of those international Submariners taking part.

For those who fail the course, around a third of them, it will be the end of their days onboard submarines, hence the name Perisher.

Proof, if were needed, of how tough the process is that since the start of the submarine service there have only been around 1,000 people that have ever passed it – a very select club.

We hear from those who have taken part in Perisher and those who taught it.