Caernarfon Harbour Trust is the authority responsible for the control of navigation and the provision and maintenance of navigational aids in the area from Britannia Bridge to Caernarfon Bay. It is also the competent Harbour Authority responsible for the provision of pilotage throughout the Menai Strait.

The Trust provides and maintains a number of moorings in the River Seiont and Port Dinorwic. Additionally, it also serves as manager for Victoria Dock Marina, Caernarfon.