You feel the same cold the fish and crabs think of as normal. You can use the full band-width of your eyes, with your nose pressed right up against a view port. This is a vastly better view than ANY video arrangement can give you. What most ROV users and operators seem to constantly strive for is to come up with a new toy, a gimmic, that makes the ROV experience as real, as informative, as looking at something that is perfectly at home in its own inaccessable, extreme environment, and only a foot or so in front of your face. Try watching a TV from only a foot away sometime.
Truth is ROVs are better for sonar survey work and taking pictures.
But don't just ask me, ask anyone who has dove to a hydrothermal vent and also been along on an ROV cruise. They'll tell you the ROV was very nearly as good as being there again. But only almost. A Diver's point of view - Veronique Robigou, Marine Geologist. But, I would have never gotten such a good comprehension of the seafloor, had I not dived in submersibles like Alvin.