Bikini Atoll has lots and lots of radioactivity. Also, sharks

The true beginning of the nuclear age was at the Manhattan Project, but it was perfected at the Bikini Atoll in the Pacific.

From 1946 to 1958, the U.S. government tested 67 nuclear devices at the site, including the one below, detonated as part of Operation Castle Bravo.

Image: U.S. Department of Energy

It was a thousand times more powerful than the Hiroshima blast, but its incredible destructive force was brief compared to its long-lingering aftermath.

To this day, the atoll's soil is contaminated with radioactive elements. The original islanders, removed to make way for the tests, were allowed to return in the 1970s, but had to leave after only a few years after it was clear it was still not safe to stay.

Even today, modern visitors aren't allowed to eat anything grown there, according to the Huffington Post. So why go there at all?

Simply put, it's a paradise for SCUBA divers with the foresight to bring a packed lunch. As part of the tests, the U.S. Army sank several decommissioned warships, including aircraft carriers. They wait below the waves for people prepared to make the journey.

They have to be careful, though. The place is teeming with sharks. The International Union for the Conservation of Nature says insulated from the radiation beneath the waves is a rich and diverse biosphere, untouched by regular human habitation.

Some 50 of the reef's 183 coral species are endangered, but thriving at Bikini, thronged with 360 different species of fish, along with numerous sharks, three kinds of which are endangered also, with tiger sharks also emerging at night.

But the IUCN says climate change and illegal fishing are a threat to the region, and if not checked, they pose a greater threat to its biodiversity than the most powerful weapons devised by man.

Miyake Jima's residents have to carry gas masks at all times

When your home survival kit includes a gas mask, it's possible you may want to rethink your choice of abode.

So it is with the residents of Miyake Jima, on a small island near Japan which is dominated by the 1,100-metre Mt. Oyama, which the Wall Street Journal says is one of the country's most active volcanoes.

Atlas Obscura says the cone erupted at least eight times in the 20th Century, and a massive eruption in 2000 forced the evacuation of more than 3,000 residents.

The authorities allowed them to return in 2005, although the evacuation order wasn't lifted in all areas until 2011, and it seems they are now required to carry gas masks at all times, due to the risk of sulfur emissions rising suddenly.

The thing is, we're pretty sure that community is well-used to that restriction, based on the numerous black-and-white shots of people wearing the gear throughout history (you can see a good selection in the Spanish-language documentary below).

Inhabited for hundreds of years, the island became a favourite destination for exiles. Today it's a great tourist spot, not far from Tokyo, not just due to its weird history, but also because the island is just stunningly beautiful.

Just be prepared to bundle in a gas mask with your flip flops if you visit.