The pursuit of the world’s tallest waves inspires surfers and scientists to explore the ocean’s most extreme phenomena. The term “tallest” refers either to massive, rideable waves generated by sustained weather patterns or absolute, non-surfable behemoths created by catastrophic seismic events. Understanding the forces and locations that produce these ocean giants requires recognizing the differences in how wave height is measured and defined. This distinction is necessary to compare wind-driven swell with the sudden, destructive waves that hold the all-time records.
Defining Wave Height and Measurement
The height of a wave is measured differently depending on its context, leading to two primary definitions. For oceanographers and forecasters, the most common metric is the significant wave height (Hs), a statistical calculation. This value represents the average height, measured from trough to crest, of the highest one-third of waves recorded over a specific period. This statistical method attempts to quantify the wave height a trained observer would visually estimate at sea.
In contrast, the surfing world often uses the actual crest-to-trough distance of a single wave face. This determines the vertical height between the lowest point of the trough and the highest point of the breaking crest. Official records for the largest surfed waves rely on photogrammetry, where judges use the surfer’s known height as a scale to calculate the wave’s face height from footage. Objective data for significant wave height comes from buoys and satellite altimeters, while surfed wave records are derived from visual analysis of the ride.
The World’s Tallest Surfable Waves
The undisputed capital of the world’s tallest surfable waves is Nazaré, Portugal, home to the largest wave ever ridden. German surfer Sebastian Steudtner holds the Guinness World Record for surfing a wave measured at 26.21 meters (86 feet) at Praia do Norte in 2020. Nazaré’s consistent production of immense waves has transformed the fishing town into the epicenter of big wave surfing, attracting athletes who specialize in tow-in surfing.
Other locations in the Pacific Ocean also produce colossal waves. Jaws, or Peʻahi, on the north shore of Maui, Hawaii, is famous for its fast, barreling waves that can reach face heights of 18 meters (60 feet) or more. Jaws was a proving ground for tow-in surfing, a technique using a jet ski to pull the surfer onto the wave face.
Mavericks, located off the coast of Half Moon Bay, California, regularly sees waves cresting over 7.5 meters (25 feet) and occasionally exceeding 18 meters (60 feet). The waves at Mavericks are known for their cold water, immense power, and the danger posed by the shallow, rocky reef beneath the surface.
The Science Behind Extreme Wave Formation
The formation of the world’s largest surfable waves results from a phenomenon known as wave focusing, driven by specific underwater topography, or bathymetry. This process requires a deep-ocean swell to interact with a sudden change in the seafloor depth near the coast.
The size of the waves at Nazaré is primarily due to the Nazaré Canyon, a colossal underwater gorge that runs 230 kilometers long and reaches depths of over 5,000 meters. This canyon acts like a funnel, channeling deep-ocean swell energy directly toward the shoreline of Praia do Norte. The canyon’s depth allows the swell to travel without losing energy until it abruptly collides with the continental shelf just offshore.
As the deep-water wave train exits the canyon and hits the shallow shelf, it is forced to slow down and compress, causing a large increase in wave height through shoaling. Simultaneously, the canyon causes the wave energy to refract, focusing waves from different directions to converge at a single point. This convergence, combined with a second wave train traveling over the shallower shelf, creates a constructive interference effect, amplifying the resulting wave face.
Absolute Records: Non-Surfable Waves
The absolute tallest waves recorded in history result from geological events, not wind and swell. These non-surfable giants are defined by their maximum run-up height, which measures the vertical distance the water travels up a slope.
The record for the tallest wave run-up belongs to the megatsunami that occurred in Lituya Bay, Alaska, on July 9, 1958. An earthquake triggered a rockfall into the narrow bay, displacing a large volume of water and generating a wave that stripped vegetation from the opposite mountainside up to a height of 524 meters (1,720 feet). This event demonstrates the power of waves created by sudden displacement of earth.
A different type of non-surfable giant is the rogue wave, also known as a freak or monster wave. These are transient, unpredictable phenomena defined as waves that are more than twice the significant wave height of the surrounding sea state. The first instrumentally recorded rogue wave was the Draupner wave, detected by a laser sensor on an oil platform in the North Sea in 1995. This wave measured a crest-to-trough height of 25.6 meters (84 feet) in a sea state where the significant wave height was only about 12 meters.