Drove down into a lakebed one time at my wifes request. Didn't think much of it, cause it was all rocky and not much sand. Didn't bother to air down, or lock in the hubs. Made it quite a ways in, then suddenly the back end just sunk. I stopped before it got too bad, winched myself out, and promptly locked in the hubs.
It had started raining by this point, and I was going to pick up my kids who had wandered down the lake-bed a bit. I turned around, and started back out. Made it about 200' and all 4 just started sinking. Buried it to the frame-rails. Fortunately I had all my recovery gear with me (always do), but still took 6 hours of digging, winching, swearing, freezing and cussing before it finally came free. I actually think the reason I got out OK, was 'cause it started to freeze, and the ground became more solid.
Lesson learned: Treat every off-pavement excursion like it may turn serious, even if it don't look bad.
Erik