BBC travel North Yorkshire

The most alluring things in life are often those that are off-limits. And as travellers, this means that we’re fascinated by places that we’re not allowed to visit. To locate some of these oh-so-tantalizing wonders, we turned to question-and-answer site Quora.

From an isolated Pacific island without running water to a James Bond-like spy base in England, here are five of the world’s most secretive places.

Svalbard Global Seed Vault, Norway

Imagine a world forever changed by a massive natural disaster: Earth’s population ravaged, its infrastructure devastated, its food sources decimated. A lone survivor’s mission: to rebuild.

In such a Hollywood-inspired apocalyptic scenario, where does a hero go? Enter the Svalbard Global Seed Vault in Norway, humanity’s last stand against a global food crisis.

Located 120m inside a sandstone mountain on the Norwegian island of Spitsbergen in the remote Arctic Svalbard archipelago, 1, 300km from the North Pole, the Svalbard Global Seed Vault is the most highly secured, robustly guarded seed bank in the world.

Opened in February 2008, the vault guards Earth’s crops against global catastrophe. With 250 million crop seeds from around the world packaged in special four-ply packets and heat-sealed to guard against moisture, it provides samples of seeds that may be lost due to accident, equipment failures, funding cuts and natural disasters.

There’s a reason scientists chose Spitsbergen: the island isn’t rocked by tectonic activity, has preservation-boosting permafrost and is 130m above sea level, ensuring the site will remain dry – and the seeds safe – even if global warming causes ice caps to melt. So secure is Spitsbergen, in fact, that studies project seeds could survive there for hundreds, if not thousands, of years.

Ni’ihau, Hawaii

Ni’ihau, the smallest inhabited Hawaiian island, may appear to be the ideal tropical escape – after all, it’s home to swaying palm trees, endangered animals and virtually no tourists – but it’s not. That’s because this 180sqkm Pacific island is off-limits to outsiders.

Sold by Hawaii’s King Kamehameha in 1863 to the prominent Robinson family – who were wealthy plantation owners – the island has outlawed outsiders since 1915. Life on the isolated island is unusual: its roughly 130 permanent inhabitants, who are Native Hawaiians, live rent-free, and do without paved roads, telephone services, plumbing, running water or stores. Horses and bicycles provide transportation, solar power provides electricity and barges deliver groceries from nearby Kaua’i.