9 Deep-diving Facts About the Lands of Oceania

Oceania is an incredibly vast geographical region with boundaries that geographers can't quite agree on. It consists of Australia, and a constellation of islands, large and small, mostly located north and east of Australia. By some counts, there are roughly 10,000 such islands covering more than 100 million square kilometers (38,600,000 square miles) of ocean surface, but just over 8 million square kilometers (3 million square miles) of land.

The region's so enormous that if you include surface water and surface land, it's bigger than all the other land area on Earth – combined.

Most of the islands are downright tiny and uninhabited. But others, like New Zealand and the eastern half of New Guinea, are sizable by comparison.

Oceania is so enormous that geographers break it into smaller chunks. The most common subdivisions are Australia, followed by Melanesia (from New Guinea island in the southwestern Pacific Ocean to Tonga); Micronesia (more than 600 islands in the Pacific, like Palau, Kiribati and the Federated States of Micronesia); and Polynesia (more than 1,000 islands including New Zealand, Cook Island, Samoa and Hawaii.)

People have lived in Australia for at least 60,000 years, and they reached the Solomon Islands about 30,000 years ago. But in other tiny remote areas of Southeast Asia, humans are relative newcomers, having arrived just 1,000 years ago.

How they did so befuddles many scientists, who struggle to see how prehistoric people with few instruments could possibly navigate the vast waters separating these far-flung outposts.

Oceania is known for its cannibalistic past. In 1839, two British missionaries visited Erromango, part of the Vanuatu archipelago, which in older times was called Martyr's Island. They were devoured by the locals. Anthropologists believe that cannibalism was practiced in that area until at least 1969. One local in 2008 even gave out the recipe for cooking a human after killing (baking time is three to five hours.)

On Fiji, the practice of human flesh eating survived until at least the 1800s. The belief was that eating your enemies transferred their power to you. Even in 2011, there were reports that a German tourist was eaten in French Polynesia, though experts think it was more likely a garden-variety murder with the killer trying to burn evidence of the body. Nowadays, "cannibal tours" are offered for tourists, and souvenir shops selling "cannibal dolls" are abundant in the Pacific Islands.

Some sources estimate that sheep actually outnumber people in Oceania. Most of its landmasses are sparsely populated, but there are roughly 42 million people living there, strewn throughout 14 different countries.

Australia (25 million) makes up most of the population, followed by Papua New Guinea (9 million), New Zealand (5 million), Fiji (1 million) and the Solomon Islands (nearly 700,000). The remaining countries are Federated States of Micronesia, Kiribati, Marshall Islands, Nauru, Palau, Samoa, Tonga, Tuvalu and Vanuatu.

Territories and dependencies include American Samoa, Cook Islands, French Polynesia, Guam, New Caledonia, Niue, Northern Mariana Islands, Pitcairn Island, Tokelau, and Wallis and Futuna. Niue and Tokelau are the least populated places in Oceania — less than 1,700 people each.

No wonder the region is called Oceania — water is Oceania's defining feature. Most of the region is under the Pacific Ocean — just 8 percent is aboveground (as we said earlier 100 million square kilometers of ocean but just 8 million square kilometers of land). Given its small percentage of landmass, perhaps it's no surprise that Oceania's population density is just eight people per square kilometer (roughly three people per square mile).

Safety alert: please do not try this at home.

On the southern tip of Pentecost Island, Vanuatu, the local men practice what's called Gol, or Nanggol – land diving. They construct haphazard-looking stick towers, tie vines to their ankles and then jump off headfirst.

These plunges see the hurtling bodies reaching speeds of 45 mph (72 kph) or more. And the most successful dives are the ones where the men can tuck their heads at the last moment and lightly brush their shoulders against the ground, stopping just short of certain death.

Good dives – ostensibly, the ones where people survive – supposedly ensure a bountiful yam harvest. The event is now a tourist attraction and is considered the progenitor to modern bungee jumping, only without any safety features whatsoever ... unless you count forest vines. The country has tried to get royalties from adventure companies that apparently ripped off the practice.

As the planet warms due to climate change, rising seas are encroaching on Oceania's islands. One Polynesian island, named Tuvalu, about halfway between Australia and Hawaii – is, as the locals say, "sinking."

As the waters rise, the beaches are slipping under the waves, slowly devouring this small island. Crops fail to thrive in the salty soil. Climate change-related illnesses (like ciguatera poisoning from consuming fish that eat micro-algaes expelled from bleached coral) are increasing. Tuvalu is home to 11,000 people and is the fourth-smallest country on Earth. But it may not be home to anyone in the next 50 to 100 years, or perhaps even sooner. The island of Kiribati is also "disappearing."

Oceania is home to dozens of UNESCO World Heritage Sites. These sites meet stringent criteria for their importance in relation to cultural, natural or historical landmarks.

In that regard, Oceania contains an embarrassment of riches. Here, you'll find UNESCO World Heritage sites like Australia's famed (and dying) Great Barrier Reef, Hawaii's Mauna Loa (the largest active volcano on the planet), the Auckland Islands, the Sydney Opera House and Bikini Atoll in the Marshall Islands.

And how about Mount Cook National Park, which protects New Zealand's tallest mountain? There's also Fraser Island, the world's largest sand island, and the Phoenix Islands Protected Area, which preserves one of the biggest remaining oceanic wildernesses on Earth.

Due to its sheer sprawling size, Oceania includes millions of people living in starkly different circumstances. Australia and New Zealand both land in the top 10 of the United Nations Human Development Index, which shows where countries rank according to standard of living, life expectancy and other factors.

Near the bottom of the list lie Kiribati, Tuvalu, the Solomon Islands, and Vanuatu. These are some of what the U.N. calls the Least Developed Countries. For example, the gross domestic product per capita in Australia is more than $51,000 while in the Solomon Islands it is around $2,400. New Zealanders can expect to live past 82 years on average; on Vanuatu, the average is 70 years.