My dad bought these for all his kids this Christmas — when I opened it I thought it was a joke. I mean I really thought it was a toy for little kids, but he pulled up some [videos on YouTube](https://www.youtube.com/watch?v=vIJINiK9azc) and I was pumped to put this thing together.
The assembly is tricky and you need a [helium tank](http://www.amazon.com/exec/obidos/ASIN/B000WNIXZ4/ref=nosim&tag=brooksreview-20), but once together this is simply awesome.
I spent at least an hour playing with it at my dads, one of my cats is scared to death of it — best toy ever.
(Side note: We tried taking one outside and it floated away rather quickly. If you do this a fishing line tether is a smart play. Also achieving perfect neutral buoyancy is key.)
I have the [clown fish](http://www.amazon.com/exec/obidos/ASIN/B005FYCBR6/ref=nosim&tag=brooksreview-20), but the [shark](http://www.amazon.com/exec/obidos/ASIN/B005FYEAJ8/ref=nosim&tag=brooksreview-20) is just as awesome.