Welcome to Twemlow's Wood, a lovely place for a walk, dogs allowed and frequented by local people.
You know how watching old films and kids shows back when you were kids and they were continually ending up in a pickle in quicksand? Then as you go out in the world you can't help but note that there is a decided lack of quicksand! Well this is our ode to the youthful dangers. Of course it is not neccesary to end up neck deep, if you decide you want to "fully immerse" yourself in the cache then we would helpfully suggest full length waders, perhaps leave the phone as well, you know, just in case 
From Wikipedia...... "A human is unlikely to sink entirely into quicksand and drown at all due to the higher density of the fluid (assuming the quicksand is on dry ground and not under water, but even if underwater, sinking is still improbable). Quicksand has a density of about 2 grams per milliliter, whereas the density of the human body is only about 1 gram per milliliter. At that level of density, sinking in quicksand is impossible. Descending about up to the waist is possible, but not any further. Even objects with a higher density than quicksand will float on it—until they move."
It goes on helpfully to add.... "Continued or panicked movement, however, may cause a person to sink further in the quicksand. Since it increasingly impairs movement, it can lead to a situation where other factors such as weather exposure, dehydration, hypothermia, tides or carnivores may harm a trapped person." I don't really think tides will cause a big problem here though, so that is something hey?
Wiki really is full of fabulous advice though..... "Quicksand may be escaped by slow movement of the legs in order to increase viscosity of the fluid, and rotation of the body so as to float in the supine position (lying horizontally with the face & torso facing up)."
So there you go, we do feel we have fulfilled the health and safety part, over to you now!
For the sensible folk, you can of course achieve this without extraordinary measures..... maybe.... (perhaps bring a towel just in case!)
Enjoy! Please be gentle and of course replace as found.