The answer................when you are jumping into a river dressed in a helmet and life jacket, and someone who knows what they are talking about says it is safe! Still doesn't sound like a good idea to me though!
However, it turned out to be the highlight of a day out with our newly formed HE group, Kayaking in Llandysul!
Rhiannon poised for action
Oops - missed with the camera
Sam at the ready