How the underground maze below the Gaza Strip works

The simplicity of immersed tube tunnels

Tunnels have traditionally bored holes through the earth below the water. On the other hand, immersed tube tunnels connect hollow, massive sections in trenches along the floor of the body of water. Each section is built on land, floated to the site, submerged, and connected. This method saves money by reducing expensive underground work, and it preserves an area's aesthetic appearance.

Essential pipes, sewers, and cables lie buried beneath New York City

The Department of Design and Construction offers a tour of its work sites, explaining the complex systems that exist underground. Gas, electrical, telecom pipes, and many others, sprawl out underneath the entire city, with dozens of maps that help workers know where they're placed. This layout is unusual compared to the rest of the country, where wires are often present and visible above ground.

Enter the Mayan underworld through this 3-mile cave

Discoveries in Belize's Actun Tunichil Muknal (ATM) cave suggest the cave was once a significant site for sacred Mayan ceremonies in antiquity. New research reveals how the Mayans conducted rituals to re-enact a specific creation myth, often staged in desperate times and aimed to invoke the gods for a "rebirth" amid drought and turmoil. Read more on the enigmatic research here.

A West Berlin student dug a tunnel under the Berlin Wall—29 East Germans escaped

This podcast recounts how a young West Berlin student excavated a secret 135‑meter tunnel beneath the Berlin Wall in 1962. A total of 29 East Germans escaped to freedom, even as a Stasi mole threatened exposure.

Toronto's downtown has 18 miles of underground pedestrian tunnels

Known as the "Path," these tunnels have helped reduce pedestrian traffic on Toronto's busy downtown streets for over a century. They were first built by local business owners, prompting a network effect of add-on tunnels.

The underground cities of the Byzantine Empire

This TED-Ed video explores the mysterious cave cities of Cappadocia. Although their oldest sections may go back to the Bronze Age, most of these subterranean complexes were excavated during the Byzantine period, when the locals went underground to take shelter from Arab raiders. Monasteries were also cut into pinnacles of the local tufa, and decorated with frescoes that have often survived to the present.

In 1963, a basement renovation in Turkey revealed a passageway to a hidden, multilevel underground city that once housed as many as 20,000 people.

What it's like to go inside the Great Pyramid of Giza

Tourists can actually enter the ancient wonder, taking a 15-minute jaunt through tight spaces some describe as uncomfortable. The focal point of the journey is the chamber of the dead pharaoh, historically significant but not always visually compelling. The author describes it as a cool bucket list item but wouldn't repeat it.

Why are ancient ruins underground?

When cities fall into disrepair, it's often easier to flatten what you can and build on top. This is why modern archaeologists frequently discover ruins underground, revealing generational layers of cities rebuilt over time. This video explores major examples of this principle, from ancient Troy to even modern Seattle.

One graffiti artist turned a train tunnel into his gallery

Chris Pape, also known as Freedom, began exploring a tunnel under Manhattan's Riverside Park when he was a kid. As he grew more involved with graffiti, he turned its walls into a massive art project, one that reflected both the history of graffiti and the people who made the tunnel their home.

Inside the most crowded place on Earth

Once the densest place on Earth, Kowloon Walled City was a chaotic labyrinth of stacked homes, hidden corridors, and thriving underground life.

NYC's first subway was built largely in secret

In 1870, Alfred Ely Beach secretly tunneled under Broadway in 58 nights, disguising his pneumatic subway as a mail tube to fool Tammany Hall, the corrupt political machine that ran New York City. Nearly half a million New Yorkers rode it before politics, and a stock market crash killed the project.

What can be found underneath the Saharan sands?

Watch this 19-minute video to learn more about what can be found under the Sahara Desert, which spans almost all of northern Africa and is one of the largest deserts in the world. Deep under the Sahara desert sands lies evidence of life that once...

How flooding the Dead Sea could help the climate

There are many dead zones in the world with low elevation and very little rainfall that provide little to no benefits to the ecosystem or climate. This digestible, thorough article explains how piping in nearby water to flood these areas could...

In 2017, a hidden chamber was found in the Great Pyramid of Giza by measuring particles created in the collisions between cosmic rays and atmospheric particles.

The Manhattan Project created secret cities that didn’t appear on maps

To maintain secrecy, the US built three remote research facilities and entire “secret cities” to house thousands of workers and families. These communities—home to tens of thousands—were omitted from official maps until after World War II.

While constructing the tunnel connecting the UK and France, satellite positioning systems were supplemented by paleontologists on either side of the tunnel, who analyzed fossils to ensure excavation was at the correct depth.

Modern landfills use layered liners, leachate systems, and gas monitors to safely contain waste

Today, landfill engineering is far more complex than a hole in the ground, which was largely the system cities used less than a century ago. This video explains how it actually works.

Thunderquakes—seismic waves created when lightning strikes the ground—have enabled scientists to image underground environments near Earth's surface by detecting vibrations along subterranean fiber-optic cables.

The story of Palestine through the eyes of its people

Issues of identity are crucial to understanding Israel-Palestine. This site weaves individual narratives with key historical moments and common Q&As around the Israeli-Palestinian conflict. Ordinary people share personal stories about surviving massacres, displacement, and military occupation. And young Palestinians from across the world reflect on their identity, life under occupation, exile, and future aspirations. Explore what it means to be Palestinian through this interactive site by Al Jazeera.

Manholes connect underground sewer and water drain pipes

Wherever a portion of sewer is connected to another, a manhole is built. These serve both as access points for maintenance and as connectors for the system. This video shows how crucial manholes are for proper sewer functioning.

Unlike the other major detectors at the Large Hadron Collider, the Compact Muon Solenoid—one of two general-purpose detectors—was built above ground and then lowered underground in sections for reassembly.

Why are subway walls tiled?

In the early days of subway tunnels, architects needed to deal with dirt and moisture and make the cavernous stations less dank and dark. Ceramic tiles were easy to clean, and their glossy, bright finish helped illuminate the cave-like areas.

The three theories explaining how the pyramids were built

There's no consensus over how the ancient monuments were built, and no blueprints left behind. But centuries of study have produced three competing theories: a simple, massive external ramp, a more complex internal ramp, or a highly sophisticated water elevator.

There is a secretive bomb-proof bunker located under the White House

Built in 1942 during World War II, the Presidential Emergency Operations Center lies beneath the East Wing. Designed to protect the president during air raids—and later nuclear threats—it remains a top-secret command site used during crises like 9/11.

Sinkholes form when underground cavities cause the surface above to collapse

These openings are typically carved by acidic water, which often forms in limestone-rich areas. However, leaking pipes, groundwater removal and extreme weather or geological activity increases the frequency of sinkhole appearances.

Human settlements may be older than previously thought

This narrative article follows an archaeological team as they sift through the remains of Nahal Ein Gev II, an ancient village near the Sea of Galilee in Israel. Abandoned about 12,000 years ago, the site has been investigated for years and...

Go inside a real beehive with this interactive

Beehives are where the magic honey-making happens, where thousands of honeybees beat their wings, throw up partially-digested nectar to further purify it into sugars, and make wax. The goings-on of a beehive—the name for a man-made habitat for...

See ten of the most amazing Mayan ruins

Hidden beneath the jungles of Mexico’s Yucatán Peninsula, Maya temples, pyramids, and cities reveal the civilization’s vast construction ambitions. Decades of archaeology have uncovered these sites, which are explored in detail in this guided video tour of 10 significant ruins.

As of 2025, LUX-ZEPLIN is the world's most sensitive dark matter experiment, which is designed to indirectly detect a potential candidate for the invisible form of matter.

Watch an ethical hacker provide a tour of the dark web

Cybersecurity researcher John Hammond explores the effectiveness of a dark web search engine, leaks from ransomware group data breaches, and a categorized index of dark web links, including some that are alleged to host malware. Many dark web sites are no longer active or host scams to fool unsuspecting visitors.

The archaeological sites uncovered through London's Crossrail Project

The Crossrail Project is an underground train system in London, which saw 26 miles of new tunnels created over more than a decade. The project provided unique access to long-buried layers of London's history, and a massive parallel archaeological excavation took place.

The hidden hallway behind Mount Rushmore and why it’s unfinished

Mount Rushmore was designed to be more than a massive monument to US presidents, and its ambitious plans were part of the reason why. This fascinating video explores its backstory, creation, and the hidden tunnel behind President Lincoln's head.

Markers along the Underground Railroad

An interactive map of all National Park Service designated sites that were part of the Underground Railroad, helping shuttle escaped enslaved people to freedom.

A basement of mechanical systems—collectively called the technosphere—supports B2

Twenty-six underground air handlers heat, cool, filter and manage the humidity of the air across the biomes of Biosphere 2. The above-ground Energy Center complex provides continuous power to these and other systems, including heating and cooling water for laboratory experiments and personal use.

Explore a searchable map of underwater cables carrying internet traffic worldwide

The Submarine Cable Map provides users with data from TeleGeography's Transport Networks Research Service on individual submarine cables, including cable owners, suppliers, URLs, landing points, lengths, and notes of interest.

Who cleans the London Underground at night?

The London Underground, also known as the Tube, services millions of people every day. After the transit system closes each evening, a crew of workers known as “fluffers” gather to clean the underground tunnels. This article sheds light on these unnoticed cleaners, covering the difficulties of their jobs and the bizarre things they’ve encountered, from ghosts to nesting pigeons.

Quicksand—a mixture of sand with clay or silt soaked in water that gives way when enough pressure is applied—is denser than the human body, meaning you naturally float inside it.

Exploring the White City of Tel Aviv, the capital of the Bauhaus style

In 1933, around 60,000 German Jews fled the Nazi regime for what was then Mandatory Palestine. Among them were six Bauhaus students, who accommodated the influx by working with nearly 150 other architects to design over 4,000 buildings that reflected their alma mater's modernist style. This Smarthistory article on the area, now a UNESCO World Heritage site, allows you to see several of its buildings from the comfort of your couch.

The Gasbuggy Project detonated a nuclear bomb to fracture underground rock formations

Part of Project Plowshare—a program aimed at finding peaceful uses for nuclear devices—the 1967 experiment sought to extract natural gas trapped within shale in underground New Mexico. Gas radioactivity was found to be excessively high for use without expensive processing, and the project was deemed an economic failure.

Landfills capture methane gas and convert it into usable energy

As organic waste breaks down underground, it produces landfill gas that is roughly 50% methane. That gas can be captured and used to generate electricity or provide heat for nearby homes and businesses.

Machu Picchu, 101

Machu Picchu was built right on top of two intersecting fault lines, which makes it even more baffling how its temples and terraces have survived for more than 500 years—especially since no mortar was used to hold the precisely cut stones together. As this three-minute NatGeo video explains, this ingenious construction method allows the stones to bounce in place when earthquakes hit, shaking and rattling but rarely collapsing.

The massive sinkholes of China

Parts of China's limestone-rich terrain is fertile ground for massive caves, where some of the world's largest sinkholes are located. Hidden away in dense, lush forests, geologists are frequently discovering new sinkholes to explore. This piece...

An interactive of the deep sea

The most advanced 'bunker-buster' bomb can penetrate 200 feet below soil or concrete

The GBU-57 Massive Ordnance Penetrator is delivered exclusively by the B-2 Spirit stealth bomber, which carries only two at a time. Using GPS-guided fins and a steel alloy casing, it burrows 200 feet underground before detonating.

View a gallery of animals found on abyssal plains, hydrothermal vents, seamounts, and other deep-sea habitats.

Explore the deepest parts of the ocean

The deeps of the Earth's oceans are some of the most extreme environments on the planet. Take a trip 36,000 feet to the deepest parts of the sea in this informative, 10-minute animated video.

The Boring Company was created by Elon Musk in 2017

While it started out as a subsidiary of SpaceX, the Boring Company became an independent entity in 2018. Musk started it with the aim of helping reduce city traffic via underground tunnels.

A simple pictorial explanation of ocean geography

Visualizing ocean geographical features, such as a coastal zone, continental shelf and abyssal plain. This article from the US Geological Survey also provides several links to diverse ocean facts.

In 2009, accidentally drilling into magma provided time capsules of volcanic glass

While drilling for geothermal energy in Iceland's Krafla Geothermal Field, magma encountered at a depth of 2,100 meters quickly formed glass upon making contact with drilling fluid. By trapping dissolved gases, volatile chemicals, and the physical characteristics of magma before cooling, the glass acts as a time capsule of ancient volcanic activity and magmatic conditions.