The Hoo Peninsula is a peninsula in Kent, England, separating the estuaries of the rivers Thames and Medway. It is dominated by a line of chalk, clay and sand hills, surrounded by an extensive area of marshland composed of alluvial silt. The name Hoo is a Saxon word believed to mean 'spur of land' or refers to the 'distinct heel-shape of the ridge of hills' through Hoo. Hoo features in the Domesday Book.