This is the floating jellyfish pool light. according to the website....
All show and no sting, these battery-operated Floating Jellyfish Pool Lights unleash a kaleidoscope of color as they float in the water. For larger pools, unleash a flotilla to create a crowd-pleasing effect.
* Crafted of durable PVC
Uses four AA batteries (included).
My only wish was for it to be solar-powered. That way you can leave it in the pool 24/7 and every night it'll light up without having you to worry about changing out the batteries or turning it off and on.