Derek the Weather is kissed by the sun in this episode which kicks off on the edge of the Rhondda Valley. He takes the plunge in The National Lido of Wales in Pontypridd on his walk between Porth and Taff's Well. 

But there's a serious element too as he follows a route commemorating the first mining disaster in Wales to claim more than 100 lives – many of them boy miners. 

Dr Erin Lloyd Jones tells the story of three young brothers who perished in that Cymmer Colliery tragedy of 1856 while Onkar Singh Purewal fizzes with excitement to learn about the history of the ‘Pop Factory' in Porth.