User blog comment:Lord Loss/Monster Hunter Theory... Blog/@comment-1758220-20120922162037/@comment-1011548-20120923185231

But Wolly Mammoths were much bigger than normal elephants overall. It's all to do with surface area:volume ratio. The bigger you are, the better you are at maintaining a constant internal temperature. Polar bears are bigger than average bears as well.

The only problem with getting big like that is you need more food to keep going. Yet there's lots of food in the Tundra...

Maybe Agna sub is smaller to navigate the caves more easily?