I wonder if that's the case with older GoPros (no pun intended!), but the GP Hero 7 is natively waterproof to 10 meters. I use a snap on case which provides mic holes on either side, a tripod mount and a lanyard - which is handy for snorkeling. On the kayak I've found the mic sensitive enough to pic up casual conversation from paddling partners. I think GP is at version 9 now, which means latest-and-greatest-tech-folks are often selling their 7s with accessories for under $200.
There's some great free editing software out there too. I started to use iMovie simply because it was already on my Mac and found it definitely adequate without a steep learning curve. I highly recommend the free tool,
Handbrake to compress it afterward for sharing files that aren't gigantic.