Tucked away in the waters south of New Zealandlies a cluster of protected islands that, for a few months each year, transform into one of the most extraordinary wildlife spectacles on the planet.

The New ZealandSub-Antarctic Islands are a UNESCO World Heritage Site comprising five remote island groups scattered across the Southern Ocean. They're among the most pristine and least-modified islands left on Earth. These islands sit at the meeting point of major ocean currents, creating some of the world's most nutrient-rich waters. The result is extraordinary wildlife densities, vast seabird colonies, and some of the most significant penguinbreeding sites anywhere on the planet. More than 50,000 penguins on islands cover just 3km². The most recent full survey counted 20,716 breeding pairs on one island and 4,904 pairs on another, plus a smaller outlying colony. To put that in perspective, it's roughly the population of a town like Shrewsbury.

The penguins don't live there year-round. They arrive for breeding season, and that window is surprisingly short. Adults typically return in September. Eggs are laid from late September into early October.

Chicks start forming creches - huddled groups - around mid-November. By mid to late January, the fledglings head out to sea. That three-to-four-month window is when the islands flip from quiet, windswept wilderness to full-on penguin chaos.

Flights from the UK to New Zealand typically take about 24 hours with one connection. From there, visitors travel south to Bluff or Invercargill on the South Island to join specialist expeditions.

Voyages to the sub-Antarctic islands typically last 8 to 12 days, with prices starting from around £8,000 per person, depending on the operator and cabin type.

Permits are required to land, passenger numbers are strictly capped, and spaces fill up quickly - often a year or more in advance. It's a long way to go. But for 50,000 penguins, most say it's worth every mile.