Renowned for its 'sound of silence.' Doubtful Sound is a pristine wilderness known for its rich flora and fauna. New Zealand Fur Seals and Fiordland Crested Penguins can be seen on many of the small islets in the entrance of the fiord, while lush rainforest lines the steep cliffs. At 421 metres deep Doubtful is the deepest of the fiords. Long and winding with three distinct 'arms'. It covers a distance of 40 kilometres from deep cove to the sea.