I'd be super keen to use something like this for biodiversity monitoring; to do surveys to find out what's down there, observe behaviour of deep ocean animals that we know next to nothing about and to document the impacts of human activities on our ocean floors! Would be a truly amazing tool.
How deep underwater do you need to go for your surveys?
I'm also building small logging devices that can be attached to things underwater, but has different architecture from ROV class of devices.
I don't have any surveys in mind but I think it would be a great application for this technology. I'm sure there is PLENTY to learn in the deep photic zone, which is 50-100m. Very hard to dive down there for any length of time.
What kind of logging device are you designing? What do you want to log?