The biggest wave ever recorded depends entirely on how the wave was formed and how its size is measured. Waves of immense scale are generated through fundamentally different physical processes, making direct comparison challenging. The largest waves are often catastrophic events, not the rolling crests seen by surfers, and are largely invisible until they make landfall. Understanding the true scale of oceanic extremes requires differentiating between wind-driven surface waves, seismic sea waves, and localized displacement events.
Understanding Wave Categories
Ocean waves are divided into three major categories based on their generation mechanism, each having a distinct potential for maximum size. The most common are wind waves or swell, generated by the friction of wind passing over the ocean surface. These waves travel in groups and are the ones most frequently observed, including those ridden by surfers.
A tsunami is a series of waves caused by the massive displacement of water, often from large-scale underwater tectonic activity like earthquakes. While tsunamis travel incredibly fast across the deep ocean, they possess a long wavelength and a relatively low height, often only a few feet. Their devastating power is realized when they reach shallow coastal waters, where their energy compresses, causing the wave height to increase dramatically.
Separate from typical oceanic tsunamis are mega-tsunamis, which result from extreme, highly localized displacement events. These are usually triggered by a massive landslide, rockfall, or a volcanic eruption collapsing into a confined body of water. This mechanism creates an immediate, localized “splash” with an initial wave height that far surpasses anything else generated in the ocean.
The Largest Documented Wave: Mega-Tsunamis
The largest wave height ever scientifically documented occurred as a mega-tsunami in Lituya Bay, Alaska, on July 9, 1958. This event was triggered by a magnitude 7.8 earthquake along the Fairweather Fault, causing an enormous rockfall into the narrow fjord of Gilbert Inlet. An estimated 30 million cubic meters of rock plunged from approximately 3,000 feet into the water below.
This sudden displacement generated a wave that surged up the opposite slope, stripping the forest bare. Scientists determined the maximum vertical height the water reached on the land, known as the run-up height, was an astonishing 1,720 feet above sea level. This measurement is the maximum elevation of the inundation zone, not the height of the wave crest itself, and was higher than the tip of the Empire State Building.
The scale of this event highlights the difference between wave height and run-up, which is the vertical distance the wave travels up a slope after breaking. The Lituya Bay mega-tsunami was an extreme, localized event whose force was concentrated by the narrow, deep shape of the fjord. This catastrophic, single-point displacement holds the record for the highest measured water mark.
The Elusive Giants: Rogue Waves
While mega-tsunamis are triggered by geological forces, rogue waves are spontaneous giants that emerge from the open ocean without warning. For centuries, these waves were considered maritime folklore, dismissed as exaggerated tales told by sailors. Modern science has since confirmed that these transient monsters are real and pose a significant threat to maritime traffic.
Rogue waves are defined by their disproportionate size compared to the surrounding sea state, typically being at least twice the height of the average waves. They form through constructive interference, where multiple smaller wave trains traveling at different speeds momentarily align. As the crests temporarily stack on top of one another, they create a single, towering peak.
The first instrumental confirmation of a rogue wave occurred on New Year’s Day in 1995 at the Draupner oil platform in the North Sea. Using a downward-pointing laser sensor, instruments recorded a wave 84 feet (25.6 meters) high in a sea where the significant wave height was only about 39 feet. This measurement provided evidence for a phenomenon that defied previous linear wave models. The Draupner wave proved that these oceanic anomalies are a recognized, non-linear physical occurrence in the deep ocean.
Record-Breaking Waves Surfed
The most relatable measure of a massive wave is the largest one successfully ridden by a surfer, representing the extreme end of wind-generated swell. The Guinness World Record is held by German athlete Sebastian Steudtner, for an 86-foot (26.21-meter) wave he rode in Nazaré, Portugal. This ride took place in October 2020 at Nazaré, a location famous for its underwater canyon that dramatically amplifies incoming Atlantic swells.
Measuring these surfing giants requires a different methodology than calculating the run-up of a mega-tsunami. The measurement involves calculating the vertical distance from the trough to the crest using photogrammetry and video analysis. Scientists use the surfer’s known height or specialized drone technology to provide a calibrated reference point against the wave face. Steudtner’s record wave was confirmed after an 18-month analysis of the video and photographic evidence.