Well, except when a beach tries to swallow you: http://www.dailymail.co.uk/news/article-3250475/A-car-caravan-camping-trailer-disappear-giant-SINKHOLE-size-foot

Well, except when a beach tries to swallow you: http://www.dailymail.co.uk/news/article-3250475/A-car-caravan-camping-trailer-disappear-giant-SINKHOLE-size-football-field-opened-Queensland-beach.html http://www.dailymail.co.uk/news/article-3250475/A-car-carava... ...or when your backyard tries to swallow you: https://www.theguardian.com/world/video/2016/aug/02/news-footage-shows-giant-sinkhole-take-chunk-of-australian-back-yard-video https://www.theguardian.com/world/video/2016/aug/02/news-foo... That is an anecdote obviously, not a widespread danger.