Beavers build lodges from woven sticks, grasses, and moss plastered with mud. These architectural marvels can be up to 8 feet wide and 3 feet high inside. A lodge is designed with at least two underwater “doors” to provide instant swimming access, while a “skylight” hole at the top lets in fresh air. There are two main rooms inside – one near the entrance that is used for eating and drying off and another used for sleeping and raising the young. On average, between four and eight beavers live in a lodge.