An ever-expanding sinkhole appeared this month in a park in Oxford, N.S. So far, it’s swallowed up large trees and picnic tables. The pit is nearly 40 metres in diameter and geologists say they aren’t sure how much bigger the crater will get. Sinkholes occur when the rock below the surface of the ground is made of soluble rock (like gypsum, the material responsible for the Nova Scotia pit), which can become weak and dissolve due to ground water. The holes often appear suddenly and can cause major destruction. Here are some eye-popping sinkholes that have appeared across Canada and around the world.