I work as a lifeguard and it is brilliant for attending uni in a few ways, the hours are great and don't wreck my sleeping routine like working in a bar did. When I'm not on the pool I can actually sit and do my uni work which is brilliant coming up to exams. The pay is better than a lot of other student jobs (£9 p/h for lifeguarding £15 p/h for swimming teaching) and should my degree not work out as planned or I struggle to find a job in a sector relating to my degree it's not a bad job to end up in. There's a lot of room for progression to management roles within the company but there's other routes you can take without moving to management such as fitness instructing or PR. You get first rate first aid instruction/qualifications and you regularly complete staff training where you practice everything you've learned (which also means you get paid to swim and do first aid once a month).
It's not a hard job to get into and you don't even have to be a brilliant swimmer, I definitely wasn't before I did the course.
If you can swim I would highly recommend looking into it.