The singular fact about Maho Beach is a measurement, not a mood. Aircraft on final approach to Runway 10 cross the sand at roughly 10 to 20 metres above the heads of people standing on the beach. To understand why that number is so low, and why it is structurally impossible to make it higher without closing the airport, you have to look at the geometry of the runway and the island.

Princess Juliana International Airport has one runway, 10/28, measuring 2,300 metres. For most of its length it runs parallel to the south coast of Saint Martin, and its western threshold, the Runway 10 end, terminates a stone's throw from the Caribbean. The airport sits only about 4 metres above mean sea level. Aircraft land on a conventional 3-degree glide slope, which means that for every metre of forward travel the aircraft loses about 5 centimetres of height. Trace that slope backwards from the runway threshold, across Beacon Hill Road and the perimeter fence, out over the strip of sand that is Maho Beach, and the aircraft is still only tens of metres up by the time it passes the waterline. There is no displaced threshold deep into the island that would let pilots fly the approach higher, and no room to relocate the runway, because the Simpson Bay Lagoon sits immediately inland. The sea is on one side, the lagoon on the other, and the beach is the last sliver of land before the wheels touch.

This is what separates Maho from the long list of beaches that happen to be near airports. At most airports the approach path crosses water, an unpopulated overrun, or a fenced buffer hundreds of metres deep. Here the public has free access to the exact patch of ground directly beneath short final. A wide-body's belly fills the sky; you can read the registration, the tyre treads, the open gear doors. The aircraft is close enough that the sound arrives as physical pressure, and small children and older people are routinely knocked off balance by the wash even of a landing aircraft, which is the gentler of the two events.

The takeoff end is where the danger concentrates. When a jet at the Runway 28 end (the Maho end is also used for departures when the wind favours it, but the dangerous blast at the beach comes from aircraft holding at the threshold nearest the fence and running up to takeoff thrust) spools its engines for departure, it produces a jet blast, a high-velocity, high-temperature exhaust stream, strong enough to throw an adult. Tourists deliberately grip the chain-link fence to ride this blast, a practice the local press calls fence-surfing. The airport's signs warn in plain language that jet blast and prop wash can cause extreme bodily harm and that closely approaching aircraft can result in serious injury and death. People do it anyway, because the entire culture of the beach is built on getting closer.

The consequence is not hypothetical. On 12 July 2017, around 6pm, a 57-year-old woman from New Zealand was holding the fence at the departure end as a Caribbean Airlines Boeing 737 ran up for a flight to Trinidad. The blast tore her off the fence and threw her backwards; she struck her head on concrete and died of her injuries. News reports at the time identified her only as a 57-year-old New Zealand tourist; authorities did not publicly release her name. Her death is the clearest demonstration of the spike's double edge: the same geometry that makes Maho a wonder makes the fence a place where a routine 737 departure can kill.

It is worth being precise about which aircraft do this and how often, because the spectacle is sometimes exaggerated. The biggest jets, the 747s, are gone; KLM's last scheduled 747 visit was 28 October 2016, and the Amsterdam route now flies the smaller Airbus A330. Day to day, the traffic is regional and narrow-body, with a handful of long-haul arrivals. But even an A320 or 737 on a 3-degree slope over a 4-metre-high threshold passes Maho at the same tens-of-metres height. The number does not depend on the aircraft being enormous. It depends on the runway sitting where it sits, between a lagoon and the sea, on an island with nowhere else to put it. That is why the spike is permanent: you cannot move the geometry, so the planes will always cross the sand low. The only variable is whether the people underneath understand what the signs on the fence are telling them.