Understanding just how deep Earth’s oceans are is a fascinating but challenging concept. The five major oceans—the Pacific, Atlantic, Indian, Southern, and Arctic—together cover about 71 percent of Earth’s surface and hold the majority of the planet’s water. Collectively, these vast bodies of water have an average depth of about 12,100 feet (3,688 meters). To put this in perspective, the average seafloor is more than twice as deep as the tallest mountains on land are high.

However, the oceans are far from uniform in depth. While continental shelves and coastal areas are relatively shallow, much of the ocean plunges to abyssal plains, mid-ocean ridges, and deep-sea trenches that extend far below the global average. Some of these trenches reach depths so extreme that they are beyond the scale of normal human experience.

The deepest known point on Earth’s seafloor lies in the Pacific Ocean’s Mariana Trench, in a location called the Challenger Deep. This point descends to around 36,070 feet (10,994 meters) below sea level, making it nearly three times deeper than the cruising altitude of most commercial airplanes is high above Earth’s surface. To visualize this, if Mount Everest (8,849 meters)—the tallest mountain on land—were placed inside the Mariana Trench, its peak would still remain submerged by more than a mile of water.

Scientists and explorers often use comparisons with famous landmarks or engineering marvels, such as skyscrapers or the Grand Canyon, to make these depths more relatable. Yet even these comparisons fall short in truly capturing the immensity of the ocean’s hidden world. The deep ocean remains one of the least explored regions of our planet, containing vast ecosystems, geological features, and mysteries still waiting to be uncovered.

Ocean Depth vs. Earth’s Tallest and Deepest Landmarks

To understand the scale of the ocean’s depth, here are comparisons with some of Earth’s tallest mountains, deepest canyons, and tallest human-made structures:

• Average Ocean Depth – 12,100 feet (3,688 meters)
  ▸ More than 2× the height of Mount Kilimanjaro (5,895 meters).
• Challenger Deep, Mariana Trench – 36,070 feet (10,994 meters)
  ▸ 3× deeper than the Grand Canyon is deep (1,857 meters).
  ▸ Nearly 1.25× taller than Mount Everest (8,849 meters) if inverted.
  ▸ Deeper than the cruising altitude of most commercial airplanes (30,000–35,000 feet).
• Mount Everest – 29,032 feet (8,849 meters)
  ▸ Would still be submerged by over 1.2 miles (2 km) of water if placed in the Mariana Trench.
• Burj Khalifa, Dubai – 2,717 feet (828 meters)
  ▸ More than 13 Burj Khalifas stacked end to end would be needed to reach the Challenger Deep.
• Empire State Building, New York – 1,454 feet (443 meters)
  ▸ It would take over 25 Empire State Buildings stacked vertically to equal the depth of Challenger Deep.