Well if you are a sprinter then I would recommend the o-lifts very highly because they are the best for developing explosive speed.
Even if you are a distance swimmer, there could be some benefit because like runners, don't swimmers sprint to the finish?
There are many benefits of o-lifts for swimmers including:
1) they will make you more explosive which translates into better times
2) there is no eccentric, or negative portion of the lift, which will greatly reduce soreness, therefore you can concentrate on swimming without DOMS
3) they will teach you further coordination...they MAKE your body work as a singular unit, which will help with overall conditioning
4) they are, in my opinion, easier to learn and therefore safer than back squats or heavy deads
you will need a coach if you want to learn the full versions of the o-lifts, but I taught myself how to do the power versions and have become quite proficient. look into the article "the perfect snatch" here on T-Nation for a place to start.