Referred to as the "Sound of Silence", there is a secluded serenity that surrounds Doubtful Sound in contrast with the better-known Milford Sound. Both are part of the Fiordland National Park, a UNESCO World Heritage Site. Lieutenant James Cook named 'Doubtful Harbour' in 1770 as he was uncertain if it was navigable under sail. Doubtful Sound is the deepest of the fiords with a maximum depth of 421 m. It contains three distinct 'arms' and several outstanding waterfalls in the area from Deep Cove to the open ocean. Your ship will spend time navigating around Secretary Island through both Thompson and Doubtful Sounds. You will enjoy the spectacular scenery from the outer decks.