Starting from Cambridge the route follows the River Cam with its banks and pastures fringed with weeping willow trees and out into the fens. The Cam Washes have been designated a Site of Special Scientific Interest because of their rare and special habitats and wildlife. Within this SSSI, Otters can sometimes be seen. Approximately north-east of Cambridge is Wicken Fen National Nature Reserve, where walkers will pass through the remains of a fragment of a Fenland wilderness of former times. Wicken Fen was the first Nature Reserve to be owned by the National Trust and has been in their care since 1899. Wicken Fen is a haven for birds, plants, insects and mammals. It can be explored by the traditional wide droves and lush green paths, including a boardwalk nature trail, giving access to several hides.