Rocks around D’Urville Island

by Sue Farley

Falling off the side of the boat, we dropped into a golden pool of light and weed, with gigantic schools of tiny blennies darting in front of us, darkening the water above as they passed over like summer clouds.

Ochres, oranges and browns reflected off the weed and rocks, and shafts of sunlight flashed through the waves as we swam at an easy 10 metres. Diving on the edge of Cook Strait is always spectacular, although not always this pretty, and the Trios Islands, near D’Urville, are no exception.

D’Urville Island has a coastline littered with piles of gigantic rocks and edged with small chunky islands. Groups like the Trios Islands and Paddock Rocks provide rich habitats for fish life and seabirds, and over a series of visits we have explored their underwater treasures. It’s not an easy place to dive at times with its active weather energising currents and strong Cook Strait seas, but a glassy day at D’Urville is like no other, and we manage to get our fair share of those.

The Trios (Kuri Pongi) are a group of three islands lying between the east coast of D’Urville and the top of the Chetwode Islands. Owned by local iwi, they are jointly managed with the Department of Conservation (DoC) but are closed to public access. Known as ‘bird’ islands they teem with seabirds that come in to squawk and screech their way through the night, leaving early each morning for another day at sea. Fairy prions, petrels, shearwaters, penguins and gulls are all noisy locals.

Our first dive was off the northernmost Trio, a tiny island of just one hectare, with a thriving colony of rare king shags living on the south-west corner. Forests of bubble keio provide shelter for thousands of blennies, and lots of brightly coloured butterfish, dainty scarlet wrasse, blue cod and red moki. The rocks are bejewelled with intensely coloured anemones and sponges in pink, purple, orange and cream, their textures providing a sumptuous contrast to the solid rock beneath them. A hidden swim-through just a few metres below the surface is wallpapered with hydroids, bryozoans and bright sponges, our torches picking out the colours in the reduced light of the tunnel like a red spotlight.

The sea around D’Urville is usually a lot clearer than the water in the Marlborough Sounds or Tasman Bay, so it’s worth the effort to get there. Solid chunks of sandstone and greywacke provide ideal habitats for fish and seals, and crayfish are usually found lurking amongst these, although not around the Trios. The geology of the D’Urville Island area is interesting in that it is a part of the greater Nelson area that slid up the fault-line from Fiordland many millennia ago.

A quick boat trip back from the Trios, through French Pass, and past the infamous Beef Barrels brings us to the Paddock Rocks at the mouth to Manuhakapakapa Bay off the western coast of D’Urville. Both the Paddock Rocks and the Trios share a volcanic composition with the western coast of D’Urville. This has created some interesting formations both above and below the water.

Maori legend has one of the larger Paddock Rocks, Tawhi, named after a Ngati Koata child kidnapped by Ngati Kuia during a battle. We know it better as ‘the rock that the boat goes through’, and the faster the better. This and most of the other pinnacle-like islands that make up this group are covered with a cloak of tenacious native plants that cling to the unforgiving rock like oysters.

Beneath the water, though, the scenery reverts to that hazy vista of rock, weed and cod. Here the water is darker than at the Trios, as we have to go a bit deeper to enjoy the scenery. But once again, sweep, butterfly perch, and clouds of tiny triplefins dart through the undergrowth. Staunch little seahorses and nudibranchs provide comic relief and the silver slick of a passing kingfish sometimes lights up a corner.

Coming from a background of sailing, where the last thing you want to do is bring a boat into these rock-infested waters, it is a real treat to be able to intimately explore places like the Paddock rocks and the Trios from a silver-hulled boat. With the area’s turbulent geological history the seafloor is a dynamic collection of pinnacles, rocks, ridges and reefs which provide a spectacular home to a diverse range of sea life, and some fabulous diving.

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