Tides
From South Wales Climbing Wiki

Note
Climbing times stated on crag pages are only very rough approximations. Consideration should also be given to current swell, wind direction, etc., and how this will effect both available climbing time and possibilities for access and retreat.
Err on the side of caution at all times and remain watchful.
The tide times (graphic and tables) displayed here are not suitable for navigation.
Mumbles Tide Predictions