A few years back, maybe '96 or so, a woman got stuck in Turnagain Arm in Anchorage, Alaska. The tide was out when she and her boyfriend (husband?) drove across the tideflats. His jeep got stuck and she hopped out to push. Turnagain Arm is notorious for its quicksands and she became mired.
Her boyfriend couldn't get her out and ran for help. The fire department came and numbers of other people but they were not able to get her out before the tide changed and engulfed her. If I remember correctly, she was 34 years old.