I’m sorry, all I see is ultimate frustration. The poor thing wants out if that cage. Like a tiger pacing in a cage, he doesn’t belong there. Habitat zoos are better. This gorilla is in jail.
The gorilla enjoys water. He may want out..but he is known for dancing in water.
This might be a habitat zoo- they all have back rooms on the enclosures for bad weather, etc., and privacy when the animals want it. You might just be seeing the back room area.
What you’re seeing is definitely not “frustration” - it’s clearly discovered the principles ice skaters know for moving on slick surfaces. The water reduces friction between the feet and the tub and enabled it to take advantage of it by swinging arms to get speed.
Throw some fruit in there and some pool toys like a heavy innertube...
If he hangs the innertube around a keeper’s neck and sets it on fire, then it’s frustration.