[1][2] In the fiords, heavy rainfall runs off from the surrounding mountains creates a permanent freshwater layer to about 5 centimetres (2.0 in) to 10 metres (33 ft) below the surface.

A layer of calm, clear and warm seawater provides a habitat for a range of sponges, corals and fish to about 40 metres (130 ft) below the surface.

A final layer of seawater, too darkened by tannins from vegetation run-off to support most marine life, extends to depths of up to 400 metres (1,300 ft).

[6] The reserve was part of a conservation strategy the Fiordland Marine Guardians launched in 2002 and presented to the Ministry for the Environment Marian Hobbs and Minister of Fisheries Pete Hodgson in 2003.

[3] The protected marine life can be viewed by diving or snorkelling, either independently or with a tourism or charter boat service.

However, members of Ngāi Tahu may remove pounamu provided they have the right authorisation, only collect by hand, keep disturbance to the site to a minimum, and only carry as much as they can in one trip.