Remotely Operated Underwater Vehicle
I am currently diving Rhenium with a 75 foot and 300 foot tether. She has a 95 watt hour battery on board which powers the ROV as well as the topsides "buoy", which you can see in the picture below. The ROV is in the top middle of the picture, and the topsides is the white item in the middle of the black oval on the right hand side.
The 300 foot tether has become the primary way I deploy the ROV from Rendezvous. Even though I rarely use all of it, the reel makes retrieval much easier than the smaller version. I generally pay out 100-200 feet of tether on the deck first in a pile so that the ROV can pull it into the water as I maneuver away.
I've used the OpenROV-branded JXD Android controller for most of my dives, but I'm not crazy about it. It has Xbox like controls, but the two sticks are the only buttons used while diving. I've found them to be very tactile, but not as accurate as I would like. You can use on-screen controls, which with the JXD are not very good because of the lack of horsepower and poor touch screen. I have used my DJI CrystalSky display (used with my drones) for a number of dives and prefer it for on-screen controls.
I dive primarily off of my boat Rendezvous around the Puget Sound area. In particular I am interested in diving around the anchorages and marinas that I visit frequently, and seeing some of the wonderful sea life that I hear divers talk about all of the time.
Here you can see the ROV ready to dive with the kevlar-reinforced tether attached, as well as the velcro holding it securely to the tail. The battery lights are also barely visible on the very stern of the ROV.
I've found diving in marinas to be the most interesting of all. There is a surprising amount of food growth in those areas, and that attracts lots of marine life. Pilings and sunken stuff tend to be the most interesting. Plus, I can do some checks on running gear and such for neighbors and friends.
I have a Trident OpenROV Playlist on YouTube with a bunch of different dives.
Here are some of my favorites - note that some of the early dives were recorded in 720P standard definition as that was the only quality available.