Read these guys for info on action cameras:
http://thewirecutter.com/reviews/best-action-camera/
A gopro is a fantastic tool for a very specific set of circumstances. They are rugged so you don't have to worry about water and dirt. They are lightweight and small so it's easy to bring them everywhere. However, they are tuned for "action" situations: they have deep depth of field and wide angles to make sure you catch the subject, and thus require a lot of day light and have a look that can be offputting. I will happily admit that my gopro started me on an obsession with photography. Although I have since moved onto a Fujifilm mirrorless system because I found I wasn't getting what I wanted in my photos. On balance, I can certainly recommend their cameras. There is no cheaper and easier way to get photos of your family out having fun. Here's a few water photos so you can see what I am talking about.
gopro: I was carrying the camera in my boardshorts pocket here- just a quick snap from the hip while I was waiting for a wave. I did need to edit in post processing to get rid of the noise
View attachment 195851
gopro: I swam out to get this one. good light, not too much done to this is post processing
View attachment 195852
gopro: This was in full sun. The color was really washed out so I used so filtering to make it more interesting.
View attachment 195853
Fujifilm. There's no way I could have got this shallow depth of field or shot in this low light with a gopro.
View attachment 195854
Fujifilm. I had to stay out of this guy's way and needed a little bit of telephoto to reach him. A gopro would have made him too small in the frame.
View attachment 195855
Fujifilm. Shallow depth of field.
View attachment 195856