An enormous sinkhole, about 32 metres wide and twice as deep, appeared near a copper mine in Chile on Tuesday, leading experts to investigate what caused it. So what does lead to these great holes in the earth? Many are marvels of nature. According to <i>National Geographic</i>, <a href="https://www.nationalgeographic.com/environment/article/sinkhole" target="_blank">natural sinkholes</a> appear when soft underground rock under land is easily dissolved — usually by running water or rain. Man-made <a href="https://www.thenationalnews.com/world/2022/08/05/worlds-most-incredible-sinkholes-in-pictures/" target="_blank">sinkholes</a> are typically found in urban centres, where development including buildings and roads compromises the underlying rock it had been built on. According to the US Geological Survey, trapped rainwater plays its part. Sinkholes cased by rain are common in East Asia and can be <a href="https://www.thenationalnews.com/world/asia/six-dead-as-huge-sinkhole-swallows-bus-in-china-1.964141" target="_blank">deadly</a>. Geologists say it is hard to predict when the top layer of rock will collapse. The <a href="https://www.usgs.gov/faqs/how-much-does-sinkhole-damage-cost-each-year-united-states" target="_blank">USGS estimates</a> that sinkholes caused $300 million of damage a year in the US, but that figure could be higher. In October, a <a href="https://www.thenationalnews.com/uae/2021/10/09/abu-dhabi-discovers-rare-blue-hole-in-arabian-gulf/" target="_blank">blue hole was discovered off the coast of Abu Dhabi</a> in the Arabian Gulf which measured around 12 metres deep and 2,000 metres wide. The rare underwater sinkhole was found just off Al Dhafra but it pales in size to<a href="https://www.thenationalnews.com/uae/environment/2021/10/12/abu-dhabis-blue-hole-how-does-this-phenomenon-compare-to-worlds-largest/" target="_blank"> the deepest blue hole, Dragon Hole</a>, which lies in the South China Sea and reaches around 300 metres beneath the seabed. Take a look at some of the most spectacular sinkholes in the photo gallery above by clicking on the arrows. If using a mobile device, simply swipe. Learn more about some of the <a href="https://www.thenationalnews.com/mena/giant-sinkholes-dot-the-landscape-in-turkey-s-karapinar-in-pictures-1.1237751" target="_blank">sinkholes</a> mentioned in <i>The National</i> stories below. <a href="https://www.thenationalnews.com/gulf-news/oman/2021/09/21/well-of-hell-meet-the-omani-caver-who-explored-yemens-strange-sinkhole/" target="_blank"><b>'Well of Hell': Omani cave team discover what lurks in Yemen’s strange sinkhole</b></a> <a href="https://www.thenationalnews.com/mena/giant-sinkholes-dot-the-landscape-in-turkey-s-karapinar-in-pictures-1.1237751" target="_blank"><b>Giant sinkholes dot the landscape in Turkey's Karapinar — in pictures</b></a> <a href="https://www.thenationalnews.com/world/now-you-see-it-now-you-don-t-massive-sinkhole-fixed-in-days-1.178163" target="_blank"><b>Now you see it, now you don’t: Massive sinkhole fixed in days</b></a>