For this, he needs a place to exit the water, where it is not under surveillance.
It has to be fairly close. Even strong swimmers are limited to a couple of miles in scuba gear.
Preferably, it would be a boat, so he could then move many miles from the crime scene without being on camera. A houseboat on pontoons seems like one of the best options, but there are others.
It appears to be a small, manmade lake. I suspect he will be caught.
There are easier places to rob. The lake that the restaurant is on and the adjoining waterways and land are Disney property. This bolsters the natural suspicion that the robber was a current or former Disney employee, perhaps even a restaurant employee. Or, in some manner, the robber was assisted by a current or former employee.