Water temperature ranges from 8 degrees in the winter to 14 degrees in the summer. Visibility can be excellent here as there is little run-off from the land with 85% of the island covered in native forest (protected thanks to the National Park) extending right down to the shoreline.

Good sites here include Octopus Island, western and eastern ends of Sydney Cove

Aquatic Life:

At least 56 species of fish have been described from Patterson Inlet. Commonly at this site you can see blue cod, blue moki, trumpeters, banded, scarlet and girdled wrasses, tarakihi, butterfish, southern pigfish, leather jackets and the ubiquitous spotties and triplefins. Copper moki can also occasionally be seen.

A larger and more charismatic local is the carpet shark which at certain times of year can many of can be seen resting on the bottom amongst the rocks. Skates also cruise the area.

Invertebrates include paua, tubeworms, 11-armed starfish, anemones, kina, sea cucumbers, nudibranchs, rock lobster, white seatulips, brittle stars, octopus, seahorses, sponges, bryozoans and scallops.

One of the more notable invertebrates you will see here are brachiopods (or lamp shells), this species is well known from the fossil records but rarely seen elsewhere in modern times.

The lack of sedimentation has created a unique situation where many species of these species, such as kina, sea cucumbers, starfish and brachiopods, are equally at home on both rocky and soft inlet floors.

A huge array of seaweed species can also be found here, including red algal mats that grow directly on the sea floor thanks again to the low sedimentation.

Warnings:

This site is a marine reserve. All life and natural features are totally protected. It is illegal to take, disturb, kill or damage anything within the reserve and anyone who commits an offence may be subject to a fine of up to $250,000 and/or imprisonment. It is also an offence to pollute or litter the reserve, discharge any firearm in or into the reserve or erect any structure in the reserve.

Directions:

Octopus Island is a dive site just inside the boundaries of the marine reserve on the northern side of Ulva Island at the northwestern end of Sydney Cove. Ulva Island is a pest-free open sanctuary for native birds in the middle of the entrance to Paterson Inlet, Stewart Island and is worth a visit itself.

Dive shops in Bluff and Invercargill can arrange dive trips here and to other sites around Stewart Island and some dive charters operate out of Bluff and Halfmoon Bay on Stewart Island itself.

To get to Stewart Island is a 20 minute flight from Invercargill or a one hour ferry ride from Bluff.