Waves originate from swells that form offshore, how those waves ultimately break and the quality of conditions are determined by a variety of factors.
One of the major defining factors for different surf breaks around the world is the bathymetry, or the depths and topography, of the seafloor.
Where do Waves Come From?
Waves are created by swell, which is created by wind.
Wind traveling over long distances transfers energy into the ocean and forms the waves in a given swell. Depending on the strength and duration of the wind, you’ll end up with different types of swells.
Groundswell, which describes a swell that has formed over a greater distance often features bigger, cleaner sets of waves.
Windswell, which describes a swell that has built closer to land often features frequent, messy, and less organized surf.
Waves begin to break as their energy moves from deeper water to shallower water – the depths and shapes of the bottom heavily influence the breaking wave’s power, shape, and direction.
Surf breaks can be classified into a few different categories:
- Beach breaks
- Reef breaks
- Point breaks
- Jetties & Piers
Beach breaks are waves that break over a sandy bottom or on the beach. Sand on the seafloor shifts with day-to-day motion of the waves and larger storms – this shift will build, break, and move sandbars along the beach and influence how and where the waves will break.
Size, shape, power, and quality of beach breaks will vary depending on what the sand is doing on the bottom and the angle of the seafloor.
Beach break waves typically break closer to shore and feature multiple peaks.
Reef breaks are often characterized by a coral or rocky reef bottom surrounded by deeper water. As a swell moves from deeper water over the shallow reef, it breaks in a predictable pattern with clearly defined peaks and take-off points.
Reef breaks are often surrounded by deeper channels that make for an easy paddle out.
Point breaks are waves that break off a headland that sticks out into the water creating a “point.”
The headland juts out towards the sea and interrupts the swell energy coming towards it. This forces the wave to break in a direction away from the point.
Depending on the size, shape, and angle of the headland, you’ll either get a right-hand point break or a left-hand point break.
Point breaks can break over any type of seafloor, but are typically characterized by the length of ride and predictable quality of wave.
Rivermouths are similar to beach breaks, but typically with more consistency. Sand from the river get deposited and positioned where the river meets the ocean and forms a sandbar.
Waves break over this sandbar, that continued to get replenished and shaped by the river.
Jetties & Piers
You can think of jetties and piers similar to point breaks. In these cases, man-made objects jut out towards the ocean and refract the energy of the waves.
Waves will break off of the object in a somewhat predictable and consistent direction.
Slabs describe waves that break in water that changes drastically from very deep to very shallow.
Whereas most waves are the result of the swell losing energy and slowing as it approaches shore and breaks over itself, slabs feature the entire wave’s energy folding over itself suddenly and violently. Teahupoo is one of the most well-known examples of a big wave slab.
Slab waves are extremely fast and powerful, and typically require a jetski to tow-in the surfer. They’re thick, heavy, and often feature a number of boils, drops, and reforms as they blast over the shallow reef.
Depending on the current conditions including tides, winds, and swell along with what’s going on on the bottom of the seafloor, you can find various types of waves at each different break depending on the day.
In general, surfable waves will range from mushy or crumbly to plunging, and will often fall on some sort of spectrum.
Spilling waves can occur when the sea bottom is more gradual, the swell is weak, or the tide is too high. These waves sort of crumble on themselves and break slowly.
Plunging waves occur when a swell moves from deep to shallow water – like a sandbar or reef. These waves break top to bottom and can feature steeper walls, faster sections, and barrels.
Some other types of waves include:
- Closeouts, which break over themselves all at once leaving the surfer with few options on where to go. Closeouts don’t always mean you can’t have fun surfing though.
- Reforms, which occur when a swell hits an outside sandbar and breaks only to mellow out and slow in deeper water until it reforms and breaks again over another sandbar or the main reef.
- Double-ups, which happen when multiple swells converge to form a larger, faster wave as it begins to break.
- Shorebreak, which describes waves that break right onto the beach in shallow water.
- Thick Waves: Thick waves or thick-lipped waves occur when water is quickly forced form deeper to shallower water (e.g. Slab waves, Teahupoo)
- Spitting Waves & Spitting Barrels: Spit refers to the blast of air that blows out of certain barreling waves. This occurs when a hollow wave breaks and closes rapidly – air and spray is quickly compressed and is forced out the opening of the wave.
- Wave pools, which are man-made waves that can range from mushy and messy to clean and hollow.
Measuring Wave Heights
When talking about surf height and the height of waves for surfing, many forecasting services and surfers rely on describing the waves in relation to an averaged sized surfer. Many of the scales used that the surfer is slightly crouched.
Most wave height scales break down something like this:
- 1′ – ankle high
- 2′ – knee high
- 3′ – waist high
- 4′ – chest high
- 5′ – head high
- 6′ – overhead
- 12′ – double overhead
Swell height is different than wave height. Swell height is typically a bit smaller than the resulting waves (depending on swell period), and measures the size of the ocean waves from crest to trough.
The height of the wave breaking in a specific location is affected by:
- Sea bottom bathymetry
- Swell strength, period, direction, and swell combos
- Wind conditions
At the same spot on a different day you can find vastly different waves and conditions. Certain swells may reveal outer breaks that might not work when the surf is smaller. Certain swell and sandbars will closeout, while other will peak and break cleanly.
What’s a Set Wave?
Set waves describe the larger than average waves of a given swell. As a swell travels through the ocean, certain waves are going to be anywhere from 1-2 times larger than most of the waves in the swell.
Sometimes set waves will arrive is groups, other times you’ll see a lone set wave, sometimes described as “the wave of the day.“