23k to sit in a tin box for months at a time?? Sign me up

This ad, unfortunately, doesn't do itself favours by not showing the typical earnings once fully qualified as a submariner.

23k is the pay for ratings after Phase 1 (basic) training, i.e. the first 10 weeks after joining. Once Phase 2 training (specific training for their role) and submarine specific training, etc, which takes around 18 months to 2 years, is done they'll be on a base salary (including a recruitment and retention pay (RRP) for being a Submariner) between 30 and 32k, plus additional benefits like RRP Submarine supplement (an extra £18 a day on top of the other RRP for working on a submarine at sea), LSA (an allowance for being away from base port, initially an additional £8.35 a day, going up every year or so to as much as £35 a day), UPA (unpleasant living allowance, £4.13 a day) and a few more. The Navy can't help itself from throwing money at submariners because they take a long time to train and become more valuable as they gain experience because there's no sideways entry or pool of pre-qualified candidates who can just step into a gap when someone quits. You have to start at the bottom and work your way up. There's regular golden handshakes to incentivise staying in as well.

So, even the most junior submarine qualified Joe is earning around £40k pro-rata for being at sea on a submarine. And that's without any civvy quals when starting the job.