Did You Know: By Raising your Legs Slowly While Lying on your Back, you Cannot Sink into Quicksand?
If you sink up to your hips or higher, bend backward. The more you spread out your weight, the harder it will be to sink.
Float on your back while you slowly and carefully extricate your legs.
Once your legs are free you can inch yourself to safety by using your arms to slowly and smoothly propel yourself. If you are near the edge of the quicksand, you can roll to hard ground.