Bay level, depth & datums

2_5metresWater levels in the Bay (the height of the water surface) are referenced to Ordnance Datum, and will generally be given as a height above this datum – AOD. Levels may vary between 4.0m and 7.5m AOD. The level at any given time may be obtained from Barrage Control.

The depth of water within Cardiff Bay is generally 2.5m or greater. Care should be taken when navigating around the Wetlands area adjacent to St David’s Hotel, where port hand lateral marks indicate safe water.

Navigation within the Bay is relatively straightforward. However mariners should note that due to potential strong currents in front of the barrage sluices, vessels should keep to the correct side of the West Cardinal Mark.

Mariners should also be aware that the area directly downstream of the sluices outside of the Barrage is an exclusion zone, as high flows present a serious health and safety risk. Under no circumstances should mariners enter this area.

Bay level, depth & datums