 At the far end of the lake complex was the South Mere, 2.25-acres (1 ha) in size, with the South Gate positioned in its eastern corner.A harbour was built south-east of the castle, which would originally have been used to receive first building materials, then later senior members of the castle household or important guests.All that remains of the harbour is its 246-foot (75 m) quay, built from basalt boulders, and it may not have been in frequent use during the medieval period, since it could only have been safely used during periods of good weather.