Hidden by CSS The Channel Islands are a group of British dependency islands in the English Channel, off the coast of France. The largest, Jersey, is known for beaches and cliff trails. Just outside the main town of St. Helier, the Jersey War Tunnels complex details the island’s WWII German occupation. Medieval Mont Orgueil Castle is on a hill on the east coast. Northwest is the island of Guernsey, with its capital, St. Peter Port.