Clearance is the key -- I wouldn't take the Subaru out in soft sand. The track that is laid down by other vehicles is usually quite deep and the vehicle will get hung up. Once the sand reaches the frame you are cooked!! Even low pressure will not save you then.
Most beaches are fairly hard and do not present a problem when moving parallel with the water, but the entrance to the beach is usually pretty badly dug up and that is where you are dead. Race point is an excellent example of beach access. The ruts are sometimes pretty deep. It goes without saying the backside would be impossible with that beautiful run up the dune. Most guys run about 9 or 10 lbs tire pressure to get over it.
Threaded Mode