 There is a visitor centre in the bog, which is frequented by nature and bird watching enthusiasts.In previous inter-glacial periods the estuary of the River Clydach and River Neath once flowed through the valley now occupied by the wetland complex.Crymlyn Bog is an historic boundary between 'South' and 'West Wales', between the lordships of Glamorgan and Gower, and between the medieval and modern (i.e.