Use a waterproof case, or waterproof video recording device. Attach the suction cups to glass/smooth tiles in the pool, or use the open hooking end with a rope or string. Get creative and you can get any amazing shot you can dream up.
~*~For the mountains may be taken away, and the hills moved out of their places, but my love will not be taken from you, or my agreement of peace broken, says The Lord, who has had mercy on you. Isiah 54:10