Question about Intex Battery pool vacuum cleaner

It will work, the question is how long. Small metal parts such as screws, springs and axles will corrode more quickly. When used in salt water aquariums: Immersion depth must be at least 35 cm (dry-running switch)

I don't know whether it works in seawater. But I use it in a pool with an electrolytic cell, and the water is also salted there.
salted. It works perfectly there.

In theory it should work but for logic I would advise you every time to rinse the hoover in fresh water after use otherwise the salt stays in, hardens and could damage the product. I would get a bucket of fresh water and start it inside so that it gets clean inside. I hope I've been helpful. Anyway it works great and we practically always have clean water without turning on the filter.