I'd recommend summer camp working for a couple of reasons. First, it gives you a fun adventures to go on during the summer. Second, you will likely receive certifications for lifeguarding and/or ropes course work that you can use outside of the summer for part time work as your schedule shifts around. Third, you have a great opportunity to get to know the other workers well as you'll be spending most of your time with one another. If you're looking to be successful, any kind of networking will be helpful for you.