Stewart Island

A cage day is a long one. Boats leave early, cross open water to the Tītī (muttonbird) Islands, anchor up, and then the day turns into waiting — the cage hangs off the stern at the surface rather than being lowered deep, guests rotate through it in shifts, and whether anything arrives is outside the crew's control. Some trips produce animals inside the hour and some produce nothing but cold and swell. Departures are cancelled for weather far more often than visitors plan for.

The permits behind the current operation carry conditions, and the arrangement is still argued over locally. The Tītī Islands are customary muttonbird harvest grounds used by Rakiura Māori, and the legal challenge that reshaped the industry was driven largely by pāua divers concerned about drawing sharks in close to waters they work; by most accounts that unease has never entirely settled. Worth knowing before booking: this is a working cultural landscape rather than a wildlife attraction, the rules have shifted once already, and an operator's actual schedule can be shorter than the season implies.

Everything else is self-organised. Paterson Inlet and the water around Ulva Island are the sheltered options — bull kelp on rock, quiet basins, almost no boat traffic, and part of it inside the Ulva Island–Te Wharawhara Marine Reserve — but there is no dive infrastructure to lean on: no scheduled dive boat, no rental counter, and a long way to help if something goes wrong. It suits two groups and nobody in between: people who want the cage and never intend to put on a tank, and experienced cold-water divers who arrive self-sufficient and treat the trip as an expedition.