We were just in a studio at SSR last week, and a 2 L bottle fit very easily, along with a case of beer, 1/2 gallon milk, 1/2 gallon OJ, container of fruit - with room left over.
The freezer is pretty cold too. We have a camelback - we fill the bladder half way with water and put it in the freezer - in the morning we fill the bladder up with water and the water stays cold for about 8 hours in FL summer heat. We didn't think the little freezer would freeze the water - but it did. We were very happy, especially with the humid weather we had - worse than any trip we have had during July or August.