The scene repeats itself every day. A family arrives at the beach with their children. Within minutes, they’re playing in the sand with buckets and shovels, digging a hole just for fun, not knowing how far it will go but having a wonderful time. But experts have recently spoken out about the “art” of digging in the sand on the beach, warning that in some cases, it can be extremely dangerous. There’s a recent example.
The danger of collapse. It happened in February on a Florida beach where there were no lifeguards. Two children, a seven-year-old girl and her nine-year-old brother, Maddox, were playing in the sand and digging when a hole more than 3-feet-deep collapsed on them. The sand buried the boy to his chest, but the girl was completely covered.
A bystander captured the horrific scene on video, which shows about 20 adults trying to pull her out with their hands and plastic buckets. Still, the hole kept collapsing in on itself. Four minutes later, the first police officers, paramedics, and firefighters arrived, but it was impossible to resuscitate the girl.
The first study. In 2007, a study published in The New England Journal of Medicine (NEJM) found that between three and five children die each year in the U.S. while digging a hole in the beach. Others are seriously injured and require CPR to survive. Among the statistics are also the cases of a 17-year-old boy buried on a North Carolina beach in 2023, a 13-year-old boy who was digging in a Utah dune, and an 18-year-old boy who was digging with his sister on a New Jersey beach.
With these cases in mind, lifeguard manager Patrick Bafford of Clearwater, Florida, said his staff warns families when a hole gets too big. Still, the problem is that sometimes they don’t realize it in time. As such, Bafford says he recommends being careful about letting children dig on the beach alone, and being watchful that they don't dig too deep.
The problem is time. Bafford says the same thing as the studies and statistics: The problem isn’t so much the area itself as the reaction time. We can all imagine sand sliding down or a wall collapsing, “but they don’t seem to envision their child being buried in the sand so quickly. Nor do they appreciate the real challenge of getting the child out of the sand once the collapse has occurred,” he explains.
Coastal science researcher Stephen Leatherman told The Conversation that digging holes in the sand may seem harmless, “but if the hole is deep enough and collapses on a person, it is extremely difficult to escape. Research suggests more people die from sand burial suffocation than from shark attacks.”
The science of grains. As Leatherman states, the dry, loose grains of sand “form a pile with a slope angle of about 33 degrees, termed its angle of repose,” which determines the process in a landslide. The angle of repose he refers to is the steepest angle at which a pile of grains remains stable, “and the force of friction between each grain determines that stability,” Leatherman explains.
North Carolina State University physicist Karen Daniels, who studies how sand moves, told Slate that beach sand can appear quite resilient: “When sand is wet, the water helps hold grains of sand together. That cohesion allows sand to be shaped into a castle, or a tall pile, or to be dug down into.”
The physics of a hole. When it comes to digging holes and building sandcastles, sand is only stable while it's wet. Once it dries out, the hole collapses in on itself. So, researchers say that a wet or dry sand pile is always on the verge of collapsing.
The slightest disturbance is enough to move a grain, causing every other grain behind the first one to follow. As such, a misstep near a sand hole can be enough to lose your balance and fall as soon as the sand begins to move.
The problem of rescue. The real danger starts here: Rescuing someone from a collapsed sand hole is difficult because the sand is heavy and unstable. “As rescuers scoop away sand to free the victim, the hole will continue to collapse under the rescuers’ weight and refill with sand,” Leatherman says.
“Rescuers have only about three to five minutes to save a person who is trapped in a sand hole before they suffocate.” For all these reasons, experts recommend that ideally, no person should dig a hole deeper than the knee level of the shortest person in the group, “with 2 feet being the maximum depth.”
This article was written by Miguel Jorge and originally published in Spanish on Xataka.
Images | Caren Florance | Carmen
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