Underwater photo/video over multiple days

I'm desperately searching for answers here, and I'm hoping some camera experts might be able to help.

I'd like to capture underwater video or timelapse still images over a period of days.  At a minimum 48 hours, and ideally 72 or more.

I understand the bottlenecks (I think), but I suspect some solution might exist with some compromises.  Temperature, battery/power source, and storage capacity seem to be the major issues.  This contraption is to document fish presence and general behavior as well as species presence in a stream environment on public property.  So there needs to be an element of stealth to the construction of the housing to prevent theft.

Game cameras or trail cameras would be a good terrestrial analogy.  Having the camera triggered by movement might be an option, though things like leaves or other non-fish items floating by might generate a lot of unusable footage that would just take up storage space.  The quality of the footage/images doesn't have to be HD or 4k.  The intent here isn't to generate footage for presentation, but rather it just has to be clear enough to identify the species and ideally individual markings on individuals.

I've found a few scientific research papers on this same concept, though they're not quite the right solution or the same conditions.  Unfortunately, I'm not funded by a university or professional scientific organization, so I'm trying to do this on a budget.  A challenge, I know.  However, given the rise in consumer-grade underwater cameras, DIY programming boards etc., I have to imagine something like this is possible with off-the-shelf components.

I'm happy to experiment and build everything, but it's a bit daunting knowing where to start with regard to the camera.  Having used gopros before, and experiencing issues with overheating, crashing, start/stopping, and battery consumption, I have a feeling they're not the best choice here.  I do have an olympus tough TG6 which might be "hackable".  Outside of that, I'm not familiar enough with cameras to know what might work.  Given the requirements, I think I need something that can record to an external source, be powered by an external battery, and possibly be triggered by IR OR record timelapse, or video depending on the resolution.  I could build a waterproof housing for everything, so the camera itself doesn't necessarily NEED to be waterproof if that helps.

I know this is an obscure question, but I figured it would be worth a shot here.  Any ideas on camera type/model that might survive in this environment/situation?  I looked at security cameras, but it seems like most of them need constant power.  I need something that can be powered by a 12v battery of some size/type.

fishy_phil wrote:

I'm desperately searching for answers here, and I'm hoping some camera experts might be able to help.

I'd like to capture underwater video or timelapse still images over a period of days. At a minimum 48 hours, and ideally 72 or more.

This is a surprisingly researchy problem... as in, commercial solutions probably don't quite cut it. I've played with this a bit because I built two half-acre ponds on my property.

The commercial solutions I'm aware of are waterproof fishing cameras designed to run down your line with a tether. Not particularly cheap and also not really rated to be underwater for days.

I personally use a lot of ESP32-CAM, and they have the nice attributes that they are fully programmable (Arduino environment), cost about $7, take a uSD card, and don't draw much power. You would have to build your own housing.

What is your budget and what maker skills do you have?