When it comes to making a splash, technique tops brute force.
In the competitive sport of Manu jumping, a flamboyant, cannonball-style splash sport from the Māori and Pasifika communities of New Zealand, the secret to record-setting splashes hinges on a butt-first, V-shaped entry and a well-timed, underwater follow through, researchers report May 16 in Interface Focus.
The insights could help athletes vying for glory at the Z Manu World Champs competition or simply liven up a backyard pool party. But they may also inform aerospace engineering, aiding in the design of hull shapes or impact angles for smoother, safer spacecraft splashdowns, says Tadd Truscott, a fluid dynamics researcher at the King Abdullah University of Science and Technology in Saudi Arabia.
Manu jumping is a decades-old summer tradition where ‘bombers’ hurl themselves off of bridges, cliffs or platforms, aiming to produce the most splash. It’s a joyful, chaotic celebration of impact, one that makes backyard belly flops look like amateur hour.
“It’s a fun thing to really master and work on your technique to get the biggest splash,” says Brad Day, a mining engineer from Hamilton, New Zealand, who created a “How to Manu” tutorial.
When biophysicist Saad Bhamla at Georgia Tech in Atlanta and lab members stumbled on Day’s video, along with clips from other Manu enthusiasts on TikTok and YouTube, the researchers were instantly captivated. Most previous splash research had focused on minimizing surface disruptions, whether to reduce damage during water landings or to perfect an Olympic dive. Popping a Manu is “the diametric opposite scenario,” Bhamla says.
Following their curiosity, the researchers extracted movement data from 50 online videos, including Day’s. On average, Manu jumpers entered the water at about a 45-degree angle, with their butts leading the way and their legs and torsos angled outward in a splash-priming V, the team found.
“To be able to shoot the water that high is a real skill,” says Scott Rice, who created the Z Manu World Champs, first held in 2024. “It really comes down to how good someone’s technique is,” and, as with most precision sports, applying the right scientific insights can elevate performance.
Using 3-D–printed projectiles, robotic divers and high-speed cameras, Bhamla and colleagues performed controlled splash tests that confirmed that the precisely angled entry proved crucial to forming a deep air cavity in the plunging jumper’s wake. “But what is more important is what you do underwater,” says coauthor Pankaj Rohilla, a biomedical engineer in Bhamla’s research group.
Bum-first entry is followed by a rapid backward roll and leg extension. This stretches out the body — and, with it, the pocket of trapped air from the V-bomb — until the gravitational pull of the water overcomes the inertia of the plunging jumper. At that point, the air cavity collapses, pinches off and shoots a towering jet of spray skyward.
But when to execute this underwater unfurling? Experiments with the splashbots revealed that timing is everything. The ideal moment depends on both the height of the jump and the size of the jumper, because both affect how deep the cavity forms.
Stretch out too early, and the body releases the air cavity before it fully develops. Too late, and the body expands after the cavity has already started collapsing, weakening the splash. Only when the robot opened up about halfway through its underwater descent did it trigger the biggest vertical plumes.
That sweet spot was fleeting but powerful, highlighting how even milliseconds can separate a good Manu jumper from a record-breaking one, says Patria Hume, a sports biomechanics researcher at the Auckland University of Technology in New Zealand. Hume and her colleagues developed the “ManuTech” platform, a combination of high-speed video capture and real-time digitization software, introduced last year at Manu competitions to judge splash sizes — with the biggest blasts soaring over 10 meters high from jumps just 5 meters above the water.
“These findings could lead to new training tools or techniques to help competitors get that edge,” she says. But the waterworks are just one element of the overall score. Competitors also earn marks for splash loudness, as captured by underwater hydrophones, along with more subjective measures of technique and pizzazz, celebrating the expressive, freeform spirit that defines the event.
“While science can help athletes improve their splash, it shouldn’t take away from the freestyle roots of the sport,” Hume says. “The creativity, flair and fun in the air are what make it so unique.”
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