[quote author=lif73d link=board=7;threadid=19676;start=0#msg307281 date=1151101906]
This is at Fraser Island.
[/quote]That is usually caused by people driving to close to running creeks on sand. If you see a creek like that on sand you will find that the water is actually running under the sand as well about 3 to 5 metres either side of the creek.
So if you drive that close to the creek the weight of the 4wd actually puts presure on the area of sand where the 4wd is and the water underneath takes the sand away causing the 4wd to sink very very quickly.
Another thing that causes this is the tide coming up. The tide is coming under the sand as well as above which causes exaclly the same problem as above.
An example of this is if you sand at the waters edge while a little wave comes in when it goes out you will feel your feet sink a couple of inches. The above picture is the same thing just on a much bigger scale.
Here a pic of a simillar thing that happens all the time on Bemont/ Blacksmiths beach near Newcastle. I managed to pull him out before it sunk like the one above but another 2 hours and it would have been the same. :P
Hope this all makes sense.
Cheers Mick.