The definition of the world’s biggest wave depends on how it is measured, as “biggest” can refer to different physical properties: the vertical height of a localized splash, the immense energy of a tectonic event, or the height of a wind-driven wave. Waves are generated by fundamentally different forces, including geological events, atmospheric conditions, and underwater topography. Understanding the scale of ocean waves requires classifying them by their origin and how their height is measured, such as run-up height on land or crest-to-trough height in the open ocean.
The World Record: The Lituya Bay Megatsunami
The definitive record for the tallest wave ever documented belongs to a single, hyper-localized event in Lituya Bay, Alaska. On July 9, 1958, a 7.8 magnitude earthquake triggered a colossal landslide of 90 million tons of rock and ice into the narrow fjord. This sudden, massive displacement created a megatsunami, distinct from a typical seismic tsunami. The impact generated a giant splash that surged up the opposite slope to an astonishing maximum run-up height of 1,719 feet (524 meters). Run-up height is the vertical distance the water travels up a slope and is the standard measurement for such localized events. The wave stripped trees and vegetation from the surrounding hillsides, leaving a visible trimline on the landscape that persists today.
Deep-Ocean Giants: Wind-Generated and Rogue Waves
Far from any shoreline, the largest waves are generated by the sustained power of wind over vast stretches of open water. These wind-generated waves are measured by their “significant wave height,” which is the average height of the highest one-third of waves recorded over a given period. The world record for the highest significant wave height measured by a buoy was 62.3 feet (19 meters), recorded in the North Atlantic Ocean in February 2013. Individual waves can reach heights far greater than this average, leading to the unpredictable phenomenon of “rogue waves.” These monster waves are defined as having a height more than double the significant wave height of the surrounding sea. Rogue waves form when different wave systems align, allowing their crests to combine through constructive interference. This temporary alignment of energy can create a wall of water up to 80 to 100 feet tall in deep water, forming and dissipating quickly. The 1995 “Draupner wave” in the North Sea, which reached a maximum height of 84 feet (25.6 meters), was the first scientifically confirmed recording of such a wave.
The Science of Seismic and Volcanic Tsunamis
Tsunamis caused by tectonic activity, such as underwater earthquakes, are characterized by their immense volume and speed rather than their initial height. In the deep ocean, these seismic tsunamis often have a wave height of less than a meter and a wavelength of hundreds of kilometers, making them virtually undetectable by ships. They travel at speeds over 500 miles per hour due to the great depth of the water. As the long-wavelength tsunami moves towards a shallow coastline, it undergoes a transformation known as shoaling. The wave’s forward motion slows dramatically as the water depth decreases, causing the energy and volume of water to be compressed. This compression forces the wave’s height to increase significantly, growing from a small swell to a towering wave or a powerful surge of water. For instance, the 2004 Indian Ocean Tsunami featured waves that reached heights of 15 to 30 meters (49 to 98 feet) in coastal areas, illustrating the destructive power of this shoaling process.
How Surfers Chase the Biggest Breaking Waves
The waves surfers seek require a specific interaction between ocean swells and coastal bathymetry to become massive and rideable. These are highly amplified surface waves. The world’s largest surfable waves occur at locations like Nazare, Portugal, where unique geological features create extraordinary wave amplification. The colossal waves at Nazare are a direct result of the Nazaré Canyon, the largest submarine canyon in Europe, which runs nearly 140 miles long just offshore. Swells travel unimpeded through the great depth of this canyon, maintaining their energy. As the swell exits the deep canyon and hits the continental shelf, it is pushed upward, amplifying its height. This amplified wave then converges with unamplified waves arriving over the shallower continental shelf, resulting in the massive, breaking walls of water that big-wave surfers ride.