The lowest elevation on Earth requires a distinction between the ocean floor and dry land. Elevation is primarily measured relative to mean sea level, which serves as the global zero point for geographic height and depth measurements. The absolute lowest point is submerged beneath the Pacific Ocean, while the lowest exposed land is found in the Middle East. These two locations, the deepest oceanic trench and the lowest terrestrial surface, are formed by radically different geological forces.
Earth’s Absolute Deepest Point
The absolute deepest known point in the world is the Challenger Deep, located at the southern end of the Mariana Trench in the western Pacific Ocean. This colossal underwater valley plunges to a depth of approximately 10,935 meters (35,876 feet) below sea level. If Mount Everest, the world’s highest peak, were placed at the bottom, its summit would still be covered by over a mile of water.
The environment in the Challenger Deep is hostile. Water temperatures hover just above freezing, ranging from about 1 to 4 degrees Celsius (34 to 39 degrees Fahrenheit). The pressure at this depth is crushing, registering over 1,000 times stronger than the pressure experienced at the ocean surface. Despite the intense pressure and perpetual darkness, specialized microorganisms and complex life forms have been observed surviving in this extreme hadal zone.
The Lowest Exposed Land Elevation
The lowest point on Earth not covered by ocean water is the shoreline of the Dead Sea, which borders Jordan, Israel, and the Palestinian West Bank. The surface of the Dead Sea currently sits at an elevation of roughly 430.5 to 439.78 meters (1,412 to 1,442 feet) below sea level, making its shores the lowest land-based elevation. This hypersaline lake is an endorheic basin, meaning water flows into it, primarily from the Jordan River, but has no outlet, leading to high mineral and salt concentrations.
The extreme low elevation is part of the Jordan Rift Valley, a larger geological feature that extends across the region. This valley is a segment of the tectonic plate boundary between the African Plate and the Arabian Plate. Continuous geological movement has caused the land to drop significantly, forming the deep basin where the Dead Sea lies.
Geological Forces That Create Extreme Depths
The formation of the world’s two lowest points is attributed to two distinct mechanisms of plate tectonics. The Challenger Deep is a direct result of subduction, which occurs at a convergent plate boundary. This process involves one tectonic plate, the heavier oceanic lithosphere, sliding beneath another plate and sinking into the Earth’s mantle.
As the Pacific Plate is forced beneath the Mariana Plate, the leading edge of the overriding plate is pulled downward, creating a deep, V-shaped depression known as an oceanic trench. This recycling of the crust happens over millions of years, forming the deepest cuts in the Earth’s surface. Subduction zones are also characterized by intense seismic activity.
In contrast, the Dead Sea’s low elevation is formed by a different type of plate movement known as rifting. The Jordan Rift Valley is a transform fault and a divergent boundary, where the African and Arabian plates are pulling apart from one another.
This lateral and extensional motion causes the crust to stretch and thin, and the landmass in the center drops down to form a rift valley. This downward movement creates a deep, linear depression, which then collects water to form the lake. The resulting basin is known as a graben.
Both subduction and rifting are driven by the movement of the Earth’s lithospheric plates. One creates a deep ocean canyon by compression and sinking, while the other forms a terrestrial trough by stretching and dropping.
The Science of Measuring Earth’s Vertical Extremes
Determining these extreme elevations relies on sophisticated methods that establish a precise reference point. That reference is the geoid, an imaginary surface that represents the mean sea level if it were influenced only by gravity and not by tides or currents. Since the Earth’s mass is distributed unevenly, the geoid is not perfectly spherical; it bulges and dips, reflecting the true gravitational shape of the planet.
To map the ocean floor, scientists use a technique called bathymetry, which is the underwater equivalent of topography. Modern bathymetry primarily uses multi-beam sonar systems that send acoustic pulses down to the seabed and measure the time it takes for the echo to return. This time-delay data is converted into highly detailed depth measurements used to create seafloor maps.
For remote sensing and large-scale mapping, satellite altimetry is also employed. Satellites measure the height of the sea surface, and since the shape of the sea surface closely mirrors the shape of the ocean floor due to gravitational pull, this data is used to infer deep-sea topography.