We use this thing everywhere there is water, little kids love this thing, the batteries last a very reasonable amount of time before needing changed, everyone who sees it wants to know what it is and that's exactly how I came to own this I saw one in a pool and had to have it, totally cool pool toy hands down

Works much better than I expected!  My children loved it.

I bought this for my 4.5 year old son.  
He had great fun with it when the first time on.
(Like chasing the snake in the bottom of the pool.) Since it is heavy, it will go down to the deepest part of the pool.  Make sure your kid can swim and dive for a long time before give him this toy.  It dive through 6 swimming lanes and my son is in hot pursude....
With the baby subbies, it slow down enought for my son to catch it.

Great fun and great idea, except it leaks water badly.  On the second time, my wife found out that the internal was soaked with water.  Battery/Motor are all rusted. On the third time, the motor is dead.

With current leaking situation in the big swim pool.  I will only recommand use it in the tub  (Then what's the point of putting in the engine if it can only be used in a small tub.)