If you fell into quicksand in real life, you wouldn't sink in like people do in the movies.
If you fall into quicksand you sink to about your hips or waist, and that's it, you're stuck. You will not be pulled under, you are in no danger of drowning.
Here's a GIF showing a man jumping around on some quicksand in Morecambe Bay.
Quicksand is a mixture of sand and water that looks solid, but acts like a liquid when you disturb it.
You're less dense than quicksand, so you can't sink unless you're holding heavy items or you struggle and make the quicksand liquify more.
It's the same principle that explains why you float in water (thanks, Archimedes). "You float much better in quicksand because it is acting as a fluid that is twice as heavy as water, which is why one only sinks to about half of one's body length," says Zimmie. "The heavier the fluid, the better things float."
To get out, just lie on your back and use your arms to pull yourself to safety, says Zimmie.
It should be easy enough to drag yourself the few feet. If you're in the middle of a larger patch of quicksand, you're in more trouble, but then how did you get into the middle of it in the first place?
If that doesn't work, you might need search and rescue to come and get you.
View this video on YouTube
Nobody will blame you if you can't get yourself out. A study published in Nature found that the force needed to pull your foot out of quicksand at a speed of one centimentre per second would be equivalent to lifting a medium-sized car (in air).
If you're in the UK and get stuck in quicksand on the beach, call 999 and ask for the Coastguard. They'll be able to pump water down to where your legs are stuck to help loosen up the sand and let you get yourself out.
So if you get stuck, call for help and then sit tight, safe in the knowledge that you'll never fully sink.
Just hope that a high tide isn't due, because then you're screwed.