Quicksand has been a silent, gloopy threat in movies for decades now. It claims a desert victim in Lawrence of Arabia, it almost sucks Alan (Robin Williams) down through the floorboards in Jumanji, and it even makes a fairly comic appearance in Indiana Jones and the Kingdom of the Crystal Skull. But it's not often these sinking sand pits are the entire driving force of a film.

In Andres Beltan's Quicksand, though — as you can probably guess from the title — it's exactly that. Of the movie's 85-minute runtime, over 45 of those are spent watching the main characters helplessly trapped in the swampy stuff. So how exactly do they end up freeing themselves in the end, and how realistic is it? Let's scrape back the mud and find out.

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What is Quicksand about?

Sofia (Carolina Gaitàn) and Josh (Allan Hawco), a couple on the brink of divorce, travel to Colombia for a work conference where they make the last-minute decision to go hiking through the rainforest together. After they're almost robbed en route, they escape into Las Arenas, an off-track area riddled with snakes that their hotel receptionist has already ominously warned them is "not a safe place".

While fleeing the robber Sofia falls into a pit of quicksand, panics, and disappears below the surface. Josh leaps in and manages to pull her back up, but the two of them quickly realise they're both stuck fast. Neither of them can move enough to get out of the quicksand, nobody knows exactly where they are in the rainforest, and there's a large snake that just so happens to have a nearby nest. Cue three quarters of an hour of what is essentially a marriage counselling session in chest-deep mud, interspersed with large ants, an angry reptile, and plenty of futile flailing.

What happens at the end of Quicksand?

Brace yourself, because things go a little off the deep end. First, Sofia and Josh attempt to consolidate all the items they have in reach, and work out what they can use. Fortunately they discover the handily-placed corpse of another quicksand victim buried just below the surface of the mud, which gives them access to a backpack containing things like binoculars and a gun.

Not far from the edge of the quicksand, meanwhile, there's also a tree stump. Sofia and Josh's first escape attempt involves cutting the backpack into strips and forming a makeshift rope, which they then unsuccessfully try to lasso the stump with. The problem? It's "eight feet short".

While all this is going on, the movie's slippery main antagonist (a large snake) slides in and takes a bite out of Josh's arm, filling him with a venom that starts to slowly kill him. As Josh circles the drain and desperation sets in, Sofia comes up with a cunning plan to get free: shoot the snake, use its corpse to lengthen the lasso, then pull herself to sweet, sweet freedom.

Sound ridiculous? Well, that's exactly what she ends up doing, and it works. Sofia tugs herself free of the quicksand, stumbles through the rainforest, and finds help just in time to save Josh too.

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Would lassoing a tree stump with a dead snake actually work?

Quicksand is a movie filled with questionable plot points. Oddly, the snake sequence may not even be the biggest. Sofia sinking fully below the surface at the beginning, for instance, is a Hollywood stereotype that was debunked by researcher Daniel Bonn in a University of Amsterdam study covered in Nature almost two decades ago. The study involved placing aluminium beads of human density in a homemade quicksand solution and monitoring the results. Crucially, while the scientists replicated the downwards pull of the sand, the beads never became more than half submerged in the substance. Fully sinking wasn't a thing.

The study also mentions that the force required to pull a foot out of quicksand that is under stress "equals that needed to lift a medium-sized car." Patience, the study explains, and allowing the sand time to settle, is actually key. Guides on escaping quicksand reflect this, advising that slow movements to dislodge the sand around you are best. So while the body of a snake is densely packed with muscle — and could therefore potentially be used as a rope — Sofia may have struggled to escape by sheer pulling force alone. If the sand was settled enough it's possible, but the most affective method would likely have involved a combination of the makeshift snake/rope and the slow movements described in the guide above.

How to watch: Quicksand is streaming on Shudder from July 14.