Yeah! The dive trips were the main reason I brought up this thread as I need a dive buddy, but I looked at the ROV project a couple of years ago and DMS is the ideal place to make it happen. There is an online ROV SIG and someplace I have a DVD with some plans and instructions for building one.
Re: underwater photography, it's pretty common nowadays for people to have a Go-Pro with a housing or another similar underwater camera, however DMS would also be a great place if anyone wants to build a custom camera housing to use underwater. There are other dive related things to build, like dive flag buoys, salvage flotation bags, heck, someone might even decide to try building an underwater scooter.