During the 1880ís Cardiff was handling more coal than any other port in the world over 13 million tonnes at its peak just before the start of the First World War.

However demand for coal slumped after the Second World War and with the increasing loss of trade to container ports coal exports had virtually ceased by the 1960s.

By the early 1980s Cardiff Bay had become a neglected wasteland of derelict docks and mudflats. But then in 1987 as part of the British Government's 'Urban Development Programme' the Cardiff Bay Development Corporation was set up ito regenerate the old derelict docklands of Cardiff and Penarth. This project included the construction of a Barrage across the mouth of the Bay with large state-of-the art lock gates on the Penarth side thus creating a 200-hectare fresh water lake.

The sheltered waters provided a safe location for the development of a large marina at Penarth which included the construction of new homes surrounding the Marina basin and fronting directly on to Cardiff Bay. 

Described as Europe's most exciting waterfront development the barrage was completed in 1999 and responsibility for the Bay now rests with the Cardiff Harbour Authority whilst the Marina is managed by Quay Marinas Ltd. The Cardiff Bay Development Corporation was formally wound up on the 31st of March 2000.