Deep Cove is an arm of Doubtful Sound, a deep indentation in the southwest coast of New Zealand's South Island. Along with the Hall Arm, which lies to the southwest of Deep Cove, it forms one of the two most remote parts of the sound from the Tasman Sea, with its mouth being 32 kilometres (20 mi) from the mouth of Doubtful Sound. Elizabeth Island lies close to the junction of Deep Cove and the Hall Arm.