Swell Waves

You don’t have to be anywhere near an ocean storm to feel its power. Big waves can travel far across the ocean, causing damage thousands of miles from the storm itself.

These waves are called swells. They’re much longer from one peak to the next than typical waves. They can reach monstrous heights close to a storm, but they calm down as they move away from it.

The waves are created by winds inside a storm. They push the water, building peaks. Individual waves overlap, creating even bigger waves. The waves can organize themselves into smooth, evenly-spaced groups.

Scientists recently analyzed the swells produced by storms in 2023 and ’24. They used measurements made by a satellite that studies the surfaces of both the oceans and bodies of fresh water. It takes images of the surface, and uses a laser altimeter to measure its height. The scientists compared the results to those from other satellites dating back to 1991.

They found that a storm in the Pacific Ocean in 2024 produced the biggest swells ever seen from space. The average height of the waves was 65 feet. Individual waves could have been much higher. And the waves were up to three-quarters of a mile long.

The swell still packed a wallop when it hit the Americas, causing damage and deaths from Canada to Peru. Scientists tracked it as it rippled outward for more than two weeks. It ranged from the northern Pacific to the tropical Atlantic—a span of 15,000 miles for some really “swell” ocean waves.