I bought one of those a few years back for my dog. When the days were especially hot in summer, I would put a few inches of water in it and he would jump in and out of the pool, run around the yard; jump back in and lie in it. Eventually between jumping in and out and his claws he put a hole in it, so I bought him a small horse trough. My husband and I had to go to the other side of the island just to get it. It was thicker, but oval. He could still jump in and out of it but he could only sprawl out in one direction. The next sized pond would have been too heavy to empty. He had a lot of fun with that.
Happy gardening in Hawaii. Gardens are where people grow.