There is! In fact, there are two -- a pacific red one (I call them Red Devilfish) -- that one was a teenage octo being about 50 lbs or so. The other one was considerably smaller, but still managed to get punched out by a feisty little shrimp!! Very entertaining!
The sole IMAX-size screen in NZ no longer shows IMAX films (having opted for new release blockbuster films instead - in Charlie and the Chocolate Factory, even Deep Roy was huge!)
However, my trip to the States (this northern summer) may provide the opportunity - tentacles crossed!