North American beaver large, webbed hind feet. The unwebbed front paws are smaller, with claws. The eyes are covered by a nictitating membrane which allows the beaver to see under water. The nostrils and ears are sealed while submerged. A thick layer of fat under its skin insulates the beaver from its coldwater environment. The beaver's fur consists of long, coarse outer hairs and short, fine inner hairs (see Double coat). The fur has a range of colors, but usually is dark brown. Scent glands near the genitals secrete an oily substance known as castoreum, which the beaver uses to waterproof its fur.
Castor Bay the bay, running towards the south. A small bark and grass area with several large pohutukawa trees offering shelter compliments the beachfront and an extended coastline stretches out to the north towards Campbells Bay. Nearby John F. Kennedy Park contains old World War II bunkers that were used to survey the Hauraki Gulf and is accessible from Castor Bay by road (Beach Road) or by walkway (from the extended coastline to the north). The northern headland of Castor Bay is the site of an old Maori pā, Rahopara, that is believed to have been last inhabited and then abandoned in