Collapsing Sand Holes: Unrecognized Beach Hazard

Beaches are the top choice for vacationers in the United States and many other countries as tourists seek out the three S’s—sun, sand, and sea. Sand is magical—perfect for playing without getting dirty.

Beaches can also be dangerous places, with most people worrying about sharks, jellyfish, and rip currents (Leatherman, 2003; Leatherman, Leatherman, and Mittelstaedt, 2023). While any of these hazards could ruin a beach vacation, there is an unrecognized beach hazard—digging holes in the sand. In fact, more people die from sand burial and suffocation than shark attacks (Maron, Haas, and Maron, 2007). Digging holes in sand might seem innocent, but if the hole is deep enough and collapses upon a person, it is extremely difficult to escape (Figure 1). Information and education are necessary to reduce this poorly known risk.

Most people think of sand as a type of material, but it is actually a size, ranging from 0.06 to 2.0 mm in diameter. Quartz sand (silicon dioxide) is the most common type of sand, except for tropical and some arid temperate coasts where coral sand (calcium carbonate) beaches are found. Material coarser than sand is not soft to the touch, lacks cohesion, and is not useable for building sandcastles. Silt and clay, which are finer than sand, make water turbid and are commonly called mud. Therefore, sand is a unique substance that is in great demand for all types of uses from computer chips (hence the name Silicon Valley) to building concrete roads and buildings (Beiser, 2018).

There are different types of sand, and each type has its own specific weight. Quartz sand when dry weighs about 1.6 g/cm³ (100 lbs/ft³). This sand is often accompanied by other minerals, including ilmenite, hornblende, and magnetite (black) and garnet (red), among others, which have a higher specific weight. Therefore, dry sand can weigh from 1.6 to 2.0 g/cm³ (100 to 130 lbs/ft³). Wet sand is heavier because of the water contained between the grains.

Dry unconsolidated grains of sand will form a pile with a slope angle of about 33 degrees, termed the angle of repose (Figure 2). The angle of repose is the steepest angle at which a pile of grains remains stable, being controlled by the frictional contact between the grains that increases slightly with increasing sand size. Wetted unconsolidated grains of sand exhibit a higher angle of repose because of surface tension between the water and sand grains that tends to hold it in place. When a hole in the beach is dug, it can hold a vertical (90 degree) angle until it starts to dry out when exposed to the atmosphere and sunlight. Then, the walls of the hole can suddenly collapse, with the sand falling upon anyone below.

By its very nature, a hole dug in sand is highly unstable. When the sand collapses into a hole from either drying out or someone standing on the wall edge, the sand fills all open spaces. In other words, there is no pocket of air available for a trapped person to breathe. Skiers trapped in avalanches have been found alive when dug out of the snow because snow is light, easily removed, and can form air pockets, unlike the cases when sand collapses.

Once the sand starts collapsing into the hole, there is nothing to stop it from filling in, trapping whoever is down below and burying them alive. Rescuing someone from a collapsed hole is problematic. The basic problem is that sand is both heavy and unstable. When a collapse occurs, rescue attempts are hindered because as sand is being removed to free the victim, the hole will continue to collapse—this makes a successful rescue very difficult. There is precious little time (3 to 5 min) to save a person from suffocation who is trapped in a sand hole.

Holes should never be dug deeper than the height of the knee of the youngest person in the group. The maximum depth should be no greater than 0.6 m (2 ft).

Sudden death from collapsing sand holes is an underrecognized safety risk associated with leisure activities on sandy beaches. There were 52 documented fatal and nonfatal cases occurring during a 10 year period in the United States (Maron, Haas, and Maron, 2007). The persons, mostly kids and primarily males (87%), were submerged after the collapse of a sand hole excavated for recreational purposes.

The victims ranged in age from 3 to 21 years. The most common setting was a public beach near the shoreline. The holes were generally 0.6 to 4.5 m (2 to 15 ft) in diameter and 0.6 to 3.6 m (2 to 12 ft) deep (Maron, Haas, and Maron, 2007). Collapse was inadvertently triggered by a variety of circumstances: digging, tunneling, jumping, or falling into the hole. These collapses resulted in the death of 31 people (60%). The other 21 persons survived by timely rescue, but many required cardiopulmonary resuscitation (CPR).

Catastrophic events related to sand hole collapse occur under circumstances often not regarded as hazardous by the general public. These events are not systematically reported, so their frequency cannot be ascertained with most data derived from news reports (Maron and Maron, 2001). There needs to be greater awareness on the part of the general public and beach authorities. Lifeguards, when present, often prevent these tragedies from occurring by getting off their stands to warn those involved and closing holes. All holes should be filled in any event as they represent a hazard from someone stumbling into even a shallow hole, causing injury to their leg.

The death of a young girl in a beach sand hole collapse at Lauderdale-by-the-Sea shocked even the most experienced beachgoers in South Florida. The seven-year-old victim was trapped in the sand while she and her brother, who fortunately escaped, were playing and digging into the sand near the shoreline. The author was called in to investigate this terrible loss of life that occurred on 20 February 2024, near the town center, which was crowded with locals and especially snowbirds from northern states. Many people must have walked by the large hole being dug but did not recognize the danger (Figure 3).

The hole was 1.5 to 1.8 m (5 to 6 ft) deep, and Good Samaritans worked desperately to free the young girl until the firefighters arrived with better equipment to recover the body and administer CPR, but it was unfortunately way too late (estimated at 15 min). A memorial was held at the beach where the young girl perished, but far more needs to be done to prevent this avoidable loss of life and avert young children from being literally buried alive.

Being buried in sand actually causes two problems that cause suffocation. The most obvious and well known is obstruction of the airway by sand. This dangerous situation arises when a person becomes buried or entrapped in sand, either partially or wholly (Benomran and Hassan, 2008). What is not widely known or appreciated is that it only takes about 45 kg (100 lbs) of sand on the body cavity to stop the ability of the chest to expand and breathe. If moist sand weighs 2 g/cm³ (130 lbs/ft³), then it would only take about 0.3 m (1 ft) of moist sand to prevent a child from breathing, even if the mouth is exposed (Pleil et al., 2021).

Time is of the essence when dealing with collapsing sand holes. Observers should call 911 in the United States or the local emergency services when abroad. Better yet, have someone else make the call while you start trying to dig the person out of the sand hole. Enlist other people to help you as long as they will not be collapsing more sand into the hole. It is best to lay down on the sand so that your body weight is spread out and not focused on the edge of the hole, like you do when trying to deal with melting ice on a lake.

Rescue efforts should be focused on exposing the mouth and removing sand from over the chest. If the mouth is exposed first, rescue breathing can be administered while other rescuers continue efforts to excavate sand from the body cavity.

If enough volunteers are available, they should be directed by one person into a coordinated effort. In order to avoid too many people crowding around the hole, which could cause additional sand collapse, just two or three rescuers should work in the immediate area of the victim, while others work on widening the excavation area, making it easier for workers in the center to remove sand. The people on the outer perimeter should use any means necessary to quickly clear sand away from the central area (e.g., buckets, shovels, boogie boards, etc.). Once the person is extricated from the hole, the most critical focus shifts to treating sand aspiration with resuscitation and clearing of the airway via manual removal, by using the Heimlich maneuver or by suctioning (Heggie, 2012).