Miranda Krestovnikoff visits a seabird paradise, the magical island of Skomer. Miranda swims with the puffins and witnesses a unique wildlife spectacle as manx shearwaters return to their Welsh home after an epic 18,000-mile migration to South America.
The imposing castle at Harlech is one of the best preserved in Britain but Mark Horton discovers how it would have looked radically different, and even more terrifying, when it was built to subdue the Welsh in the 13th century. At Porth Oer, Alice Roberts attempts to solve the riddle of the singing sands - what makes some very special British beaches whistle when you walk on them? Alice records the sounds of Porth Oer's beautiful beach to reveal its surprisingly musical secrets.
Nick Crane explores the violent history of smuggling around the gorgeous Gower Peninsula, and abseils into an extraordinary stone structure concealed in the side of a sea cliff. Now only accessible by sea or by ropes, 200 years ago this was the perfect smugglers' stronghold, but Nick learns that it had an even more mysterious previous life - as a massive medieval bird house.
Coast is co-produced with the Open University.