High Quality Content by WIKIPEDIA articles! Yell Sound is the strait running between Yell and Mainland, Shetland. It is the boundary between the Mainland and the North Isles and it contains many small islands. Sullom Voe, on the shores of which is a substantial oil terminal, is an arm of Yell Sound. The ferry to the North Isles crosses the sound, which can experience strong tides and adverse weather conditions. There are numerous shipwreck sites and several lighthouses to guide shipping. Yell Sound is mentioned briefly in the medieval Orkneyinga saga and during the 19th century there was a short flourishing of the kelp industry. Commercial fishing has long been a mainstay of the local economy and part of the sound is as Special Area of Conservation set up to protect the local wildlife.