seaside resort, Conwy county borough, historic county of Denbighshire (Sir Ddinbych), Wales, on the North Wales coast of the Irish Sea. The town, which dates from the 19th century, grew rapidly after World War I to become contiguous with Old Colwyn and Rhôs-on-Sea, with which it is linked by a 3-mile (5-km) promenade around the sandy bay. Retaining its primary identity as a resort, Colwyn Bay has become the largest town on the North Wales coast. Attractions include Eirias Park and its recreational facilities, the pier pavilion and other theatres, Pwllychrochan Woods, the Welsh Mountain Zoo and Botanic Gardens, and a Harlequin Puppet Theatre at Rhôs-on-Sea. Pop. (2001) 30,269.