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Milford Sound Marine Life

A dolphin jumps out of the water, seen from a Milford Sound Cruise from Milford Sound Lodge.

A product of its extraordinary environment, Milford Sound marine life is weird and wonderful. It lives in the steep-sided, and deep U-shaped inlet or fiord, created after Fiordland rose from the sea millions of years ago and was carved into its current shape by glaciers.


At 265 metres deep, most of the sound’s water is salty, but the top 10 metres or so is freshwater. It comes from the seven to nine metres of rainfall that the area gets every year, empty into the sound via its many rivers and waterfalls. On its way, this runoff picks up tannins from plants and soil that stain the freshwater the colour of tea. It’s still completely clean and natural, but it blocks much of the sunlight from the lower salty layer.

The seawater layer is calm and a few degrees warmer, if a little dark. When you reach about 40 metres deep there is very little sunlight getting through, so all the marine life hangs out near the surface, including many species that normally live much deeper. We’ve got a unique mix of dolphins, penguins, fish, sea stars, seals, rare black coral and much more, so there’s plenty to look at.


There’s also the option of the Milford Sound Underwater Observatory in Harrison’s Cove. You can walk out to the underwater chamber and descend 10 metres under the water to the viewing room, nestled among the coral forests on the bottom.

Through the windows, you can see a natural living wonderland of anemones, mussels, sea stars, conga eels, sponges, black coral, octopus, perch, wrasse and a kaleidoscopic myriad of sea creatures. You might even spot a dolphin, shark or seal flitting through the water.

In other parts of the world, you wouldn’t be able to see many of these creatures because they live so deep, but because of the dark top layer and the proximity of the open sea, you can see them here going about their daily business in the wild.


Wondering what’s so special about black coral? Here are a few facts to digest:

  • Unlike most coral, black coral doesn’t need warm and shallow water to thrive.
  • The millions of tiny animals usually like to colonise the dark depths of cooler waters.
  • Fiordland has the most shallow population in the world and the most numerous.
  • There are about seven million coral colonies in Milford Sound, and they’ve been building their underwater forests here for 200 million years!
  • Black coral actually appears white!
  • These tiny polyps usually live around 75 metres down, far deeper than divers can reach.
  • Here in Milford Sound, they are thriving at 10 metres — so Milford offers a rare chance to get up close to an amazing feature of the aquatic world.

Black coral is under threat around the globe because it is very pretty and makes lovely jewellery — which is not good news for the species.


These waters are also home to other rarely glimpsed sea creatures. Creatures like brachiopods, a primitive shellfish that evolution forgot, more closely related to ancient fossil shells than other clams alive today. Spiny starfish move over the underwater landscape, nibbling on seashells as they go. And colourful anemones hang like Christmas garlands from the trees of coral.

New Zealand fur seals hang out in gangs and sometimes like to swim with scuba divers, and of course, there are our two species of dolphin, the dusky and the bottlenose, which sometimes like to follow the cruise boats and say hello to tourists.

A Milford Sound local, the Fiordland crested penguin. Stay at Milford Sound Lodge to meet him.

Between August and February, you can also see the Fiordland crested penguin, which is one of the rarest penguins in the world. In fact, if you didn’t see them you would almost certainly hear them—at dusk they make quite a racket as they fight for snoozing space along the shore!

So there’s plenty of amazing sea life around Milford Sound.


The least popular inhabitant of Milford Sound would have to be the sandfly. We strongly recommend that you slather on your insect repellent, because a swarm of sandflies can seriously spoil your holiday.

The male sandfly won’t give you any grief, because he’s vegetarian, but the females are biters. They can’t do you any lasting damage, but they love to suck the blood of humans, lizards or whatever else they can find, and their bites get itchy and troublesome.

One of the first Europeans to suffer the sandfly treatment was Captain Cook, who called it ‘a most mischievous animal’. And Maori folklore has it that these little biters were introduced by a goddess who wanted to prevent people from settling here so that she could have the place to herself.


The Maori people arrived at Milford Sound not long after they had begun to settle the Land of the Long White Cloud. They found a source of precious greenstone, as well as an abundant supply of fat birds, seals and fish. They named the Sound Piopiotahi, which means ‘Place of the Singing Thrush’, after a bird that is now sadly extinct. They would set up seasonal camps and take advantage of nature’s bounty, then retreat during the winter.

According to Maori legend, Milford Sound and the surrounding fiords were carved out by the god Tu-te-Rakiwhanoa, who carved and chopped them from a solid plateau of rock. By the time he got around to creating Milford Sound, he had had plenty of practice and chiselled its steep sides with clean precision. You could think of it as his masterpiece.

Another hero, Tamatea, discovered Milford Sound while out searching for his missing wife, only to find her turned to greenstone. His tears of woe hardened to solid stone and account for the seams of translucent bowenite found in Milford’s rocks.


Hundreds of years later, along came Captain Cook and the various waves of European sealers, sailors and explorers. The newly discovered inlet was named Milford Haven in 1823 by a sealer named Captain John Grono, after the harbour town of Milford Haven in Wales, although it doesn’t bear much resemblance!

About a kilometre before the Milford Sound township you can take a five-minute detour to see the crayfishing fleet. Since the 1960’s these hardy little boats have headed out to sea for up to two weeks at a time, with a skipper and two crew who lay bait and pots along the coastline.

Most will bring in at least 150 pots of crayfish every day. Using the depth sounder, the skipper will find a good spot on the sea bed to lay a pot, and signal to the crew to push it overboard, and mark its position with a floating buoy. They fish it back out again with a long grappling hook, check all the crayfish inside and throwback the tiddlers. The unfortunate larger animals are transferred into onboard fish tanks, and ultimately end up scuttling around in tanks in Asian restaurants. Here in Milford they are transported in trucks, but to get them out of remote areas like Doubtful Sound they get a ride in a helicopter!