More ideas from Olaf
Place a plastic kiddie pool in the ground. It'd be easy to clean and looks nicer than having it above ground. Then take it out in colder months and have a fire pit!!!

Dog Pond - Place a plastic kiddie pool in the ground. It'd be easy to clean and looks nicer than having it above ground. Big dogs can't chew it up or drag it around. This is obviously more fancy than a plastic kiddie pool underground, good idea thou