Matt Baker and Margherita Taylor visit the stunning Llyn Peninsula in north Wales, known as 'Snowdonia's arm'. Margherita finds out about plans for a major blue energy project that involves harnessing the power of the tide. This may tackle energy issues, but what do residents make of it and what will be the impact on wildlife and fishing?Matt dons his wetsuit, wading into the sea to help check the health of a critical crop of carbon-capturing sea grass, and also helps launch new research into mountain goats. Joe Crowley is hoping for a close encounter with angel sharks to find out why they are appearing more frequently in Welsh waters. Adam Henson celebrates the success of the rare breeds revival, and Tom Heap investigates planning loopholes that could see park holiday homes become permanent residences and threaten some of the most beautiful parts of our countryside.