Moreso than I expected. Easily the same volume as the 2 story cage they live in on land (I set it next to the existing habitat for comparison. That's the heater pad inside it.) Just one problem, the lid is opaque. I can't exchange it because according to the site, the manufacturer no longer makes the fully transparent version and they have none of that model in stock. So, I will at some point be adding a large transparent lexan window into the lid to allow light through. Maybe some LEDs around the interior rim?