Presented by Welsh acting legend, Dame Sian Phillips, this final episode in the series, looks at some of the biggest challenges and issues facing the marine environment in Wales and the rest of the world today. We meet the conservation heroes from across Wales, each doing their bit in many ways, to help marine conservation and promote the importance of the ocean. From fishermen sacrificing profits in return for sustainability and a plastic-waste campaigner who paddle boarded around Wales to raise awareness about the pollution of our oceans to a group of underwater scuba-diving litter-pickers and a surfer who uses the sea to help people with mental health issues.