Castletown is a heritage harbour consisting of outer and inner drying harbours. It is mainly used by inshore fishing vessels, local and visiting pleasure craft and occasional coasters.
Commercial limits cargo work is only accommodated in the inner harbour through a narrow swing bridge. The berth at the Umber Quay can accommodate vessels up to the maximum of 55M, beam 8.2M, and 3.5M draft MHWS 2.6 metres MHWN and those prepared to take the hard ground.
There is a lay-by berth on the Irish Quay with Maximum length 55M however there is no breadth restriction here. 3.8M on MHWS and 2.7M on MHWN.