User blog comment:Lord Loss/Discussion of the Week: Portable 3rd Subspecies/@comment-3062343-20120527020930/@comment-1011548-20120527200106

But bigger creatures loose their heat less quickly. If you have 20 litres of water at 90 degrees C, and 500ml of water at 90 degrees C, the 500ml will loose its heat much quicker. So you think it would be an advantage for Agna Sub to be bigger.

The only thing I can think of is that it's smaller to fit in tight, winding caves better, but that seems a little unlikely.