Castletown, Isle of Man House of Keys moved from Castletown to Douglas. The Isle of Man Census 2011 lists the town's population as 3,097 (2006: 3,109) It is the fourth largest town on the island, after Douglas, Ramsey and Peel, but is also smaller than Onchan and Port Erin, which have the status of villages. The town lies on the northwest side of Castletown Bay. The opposite shore of the bay is the west coast of the distinctively-shaped Langness Peninsula. To the north-east are Ronaldsway Airport and industrial zone, and the village of Ballasalla; to the north-west the villages of Ballabeg and Colby; and
Port St Mary Railway between Douglas and Port Erin. Steam trains operate on the line several times a day during the summer season, and stop at Port St Mary. The village is served by Bus Vannin services to Port Erin, Castletown, Douglas and Onchan. Once a fishing and trading port, the village is still popular with tourists and fishermen, especially during the summer. The inner harbour, with its pier created in 1812, is tidal and dries out from half-tide. The outer harbour, created when the Alfred Pier was built in 1882, is accessible at all tide states - unique amongst the Manx ports.