Joe Crowley is on Isle Martin, a dot of an island off the west coast of Scotland, which is getting ready to host Scotland's very first seaweed festival. Joe meets the island's sole occupant, explores the magical qualities of seaweed and sees how it is at the forefront of the battle against climate change. Joe also delves into the Countryfile archives to revisit some island jewels around the UK, including the time Anita Rani visited the Hebridean island where all the farmers are women, Ellie Harrison's trip to Church Island in Northern Ireland, and Margherita Taylor surveying seals off Looe Island. And we catch up with Mari Huws on Bardsey Island, just off north Wales's Llyn Peninsula.