With 6,749 people per square kilometer, Hong Kong is one of the world’s most jam-packed cities. Nevertheless, as the territory’s population is not spread evenly, there are areas where the level of density far exceeds the citywide average, the most extreme of which is Ap Lei Chau (Aberdeen Island).

Nestled just 150 meters off the southern coast of Hong Kong Island, the tiny Ap Lei Chau is home to a whopping 79,000 inhabitants, squeezed into an area of only 1.30 square kilometers. This makes it not only the fifth most densely populated island in the world, with 61,328 people per km², but also the most crowded one, with a population of over 10,000 residents per square kilometer.

The island, which owes its name to its supposed shape of a duck’s tongue (Ap – duck, Lei – tongue, Chau – island), was formerly part of the British Empire, which ruled the island along with the rest of Hong Kong following the First Opium War with China and the ensuing Treaty of Nanking in 1841. By the time the island was reintegrated into China under the “one country, two systems” policy in 1997, it had become dotted with tall residential towers, centered around an unspoiled verdant mountain.

Over the years, Ap Lei Chau underwent massive development, including the construction of a highway and railway bridge linking the small landmass to Hong Kong Island, the building and demolition of a power plant, and perhaps most notably, a land reclamation project that slightly alleviated the island’s claustrophobic nature.

There are more than 7,100 islands in the Philippine archipelago, of which only 2,000 are inhabited. As the country’s 10 largest islands are home to the vast majority of Filipinos, the archipelago’s smaller islands often remain out of the spotlight. Tucked away about 13 kilometers north of Bohol, Caubian Gamay and Caubian Daku are a pair of pint-sized islands, nestled in the turquoise waters of Danajon Bank, the world’s largest double barrier reef and the only one in the Philippines.

Despite their relative similarity in size and sheer proximity to each other, the two islands couldn’t be more different. While the resort island of Caubian Daku has no permanent inhabitants, its slightly smaller counterpart is home to a staggering 2,249 people. As Caubian Gamay barely surpasses 4 hectares, it has a population density of 60,725 inhabitants per km², making it the country’s most densely populated island by a large margin.

The largest inland body of water in Africa and the world’s second-largest freshwater lake, Lake Victoria serves as a major source of livelihood and water for the three countries that share its borders: Uganda, Kenya, and Tanzania. Due to ongoing climate change, the lake’s water level has been receding for quite some time, leading to a series of unintended consequences. The most notable of these occurred in the early 1990s, when a tiny rock turned into a full-fledged island.

Surrounded by incredibly fish-rich waters, Migingo Island soon became a magnet for local fishermen from Kenya and Uganda, who set up their base of operations along its rugged shore. As this speck of land straddled the mid-lake Kenyan-Ugandan border, both countries claimed sovereignty over the island, triggering dozens of diplomatic skirmishes in the following years. Nonetheless, during this time, an increasing number of fishermen opted to settle on the tiny rocky islet, enticed by the area’s lucrative Nile perch industry.

In 2009, after a decade of harassment by the Ugandan police for supposedly not complying with its laws, Uganda decided to withdraw all of its troops from the island, which was then formally recognized as part of Kenya.

Covered almost entirely with rickety corrugated-tin hovels, the 2,000-square-meter island officially has a population of 131, though in practice the numbers may be much higher. Whatever the true figures are, Migingo is Africa’s most densely populated island, with more than 65,500 people per km². Somewhat surprisingly, within the island’s minuscule confines, one can find a couple of bars, a pharmacy, a brothel, and even a makeshift casino.

Stretching across the Gulf of Morrosquillo along Colombia’s Caribbean coast, the San Bernardo Archipelago consists of ten islands. While 9 out of the archipelago’s 10 islands are everything you’d expect from a tropical paradise, the tenth isle bears no resemblance to its nearby counterparts. With a size equivalent to that of Trafalgar Square in London, Santa Cruz del Islote is ridiculously small, yet it is arguably the world’s most crowded island.

According to local lore, two centuries ago, the islet was merely an elevated sea bed formed by the incessant accumulation of corals. That is, until local fishermen from the surrounding islands were lured to the unassuming spot, presumably due to the absence of mosquitoes. To cement their presence, the fishermen created a tiny isle using everything they could find, including coral stones, rocks, and garbage.

Since the late 19th century, when Santa Cruz del Islote was first formed, the semi-artificial island has witnessed a massive demographic boom. In fact, some estimates put the population at more than 1,000, all of whom are huddled into a meager 12,140 square meters. This translates to a jaw-dropping density of over 100,000 people per km². Other estimates are far more modest, suggesting the population is actually between 500 and 800.

Whether Santa Cruz del Islote is Earth’s most claustrophobic island is up for you to decide, but one thing is clear: with neither cars nor motorcycles, and no crime, it serves as a time capsule where laid-back vibes reign supreme.

Sandwiched between mainland Haiti and Île-à-Vache, Canal de L’Est is a strait whose southern half is dominated by a series of sandbars and cays. At the eastern tip of this chain of shoals lies the aptly named Caye de l’Est (The Eastern Cay), a place so extreme that even a mid-desert refugee camp might seem more hospitable to some.

Locally known as Îlet-à-Brouée, this overcrowded patch of sand spans a mere 4,000 square meters—slightly less than one acre, or roughly the size of a soccer field. With an estimated population of 500 inhabitants (most of whom are local fishermen), calling Ilet a Brouee a “sardine box” would be an understatement. In fact, with its current population density, the island has around 125,000 people per km², making it, at least on paper, the world’s most densely populated island. As the only source of income is fishing, Caye de l’Est functions like one large fish-processing plant.

If you think the isle’s overpopulation is its only challenge, think again: this speck of land is located right in the middle of a hurricane-prone region. In 2016, Hurricane Matthew trimmed a fifth of the island’s already minuscule landmass, further cementing its dubious claim as the densest islet on the planet.

Lacking basic amenities such as electricity, running water, sewage systems, education, or medical care, Ilet a Brouee is not for the faint-hearted. Almost every square inch of the island is covered by poorly built huts with walls made from straw, palm leaves, or tarps, the only exceptions being the church and grocery store (both of which are concrete buildings). To top it off, none of the island’s houses or narrow alleyways have paved floors—everything is covered by bare sand.