The Kahukura marine reserve at Charles Sound covers an area of about 464 hectares and was one of eight reserves established in 2005 as part of the management measures proposed by the Guardians of Fiordland.
The reserve provides a very sheltered habitat away from the influence of ocean swells. It encompasses the inner fiord reaches of Gold Arm, including estuarine habitat associated with the Windward River outflow and broken rocky reef habitat, with large submerged boulders around Fanny and Catherine Islands. It includes rock wall and terraced rock wall habitat at Old Point providing a sheltered habitat for a diverse community life.
Spectacular red and black corals are abundant, and on bright days with clear water these can even be viewed from a boat.