The principal harbour of the Isles of Scilly (known as St Mary's Harbour) is located on the northern edge of the town, naturally formed by the bay at Town Beach (itself part of a larger bay named St Mary's Pool) and improved by the construction of a quay on its western side, which acts also as a breakwater. The quay is the terminal of the ferry to Penzance, currently the "Scillonian III", and the cargo vessel "Gry Maritha"; both vessels have St Mary's as their port of registry. The Duchy of Cornwall is the owner and the harbour authority (the St Mary’s Harbour and Pilotage Authority).