Have you ever seen a sinkhole? Do you know what a sinkhole is? A sinkhole forms when the ground collapses. Sinkholes form naturally, but sometimes human error can cause them too. We usually call these collapses, not sinkholes. Abandoned mines can sometimes collapse. Burst pipes in urban areas can also cause the ground to collapse.

Sinkholes can happen anywhere, and anytime. They can form quickly, or gradually over time. You can find them all over the world. You can find sinkholes as deep and wide as a metre. You can also find sinkholes as deep and wide as 600 metres. Sinkholes can also be found on land or in water.

This is the Great Blue Hole. It is a large marine sinkhole off the coast of Belize. The hole is 318 metres across and 124 metres deep. It is a popular scuba diving spot. Can you imagine diving here? You can see bull and hammerhead sharks here, but not often. Bull sharks are quite dangerous but fascinating.

This is the Red Lake. It is a sinkhole found in Croatia. There are several caves, and high cliffs here. The Red Lake is about 530 metres deep. It is named after the red rocks surrounding the sinkhole. It looks so deep. I wonder what's down there.

Cenotes are a type of sinkhole that usually have water. You find most cenotes in the Yucatan Peninsula in Mexico. Cenotes form when limestone collapses to reveal groundwater. Cenotes are beautiful and magical places.

You can find cenotes that are completely underground. These cenotes are popular cave diving places.

You can find cenotes that are semi-underground. These cenotes are popular for swimming and snorkeling.

You can also find cenotes that are land level. These look like small lakes or ponds.

This is the Cenote Cristal. It is a small cenote in Tulum, Mexico. It has a diving platform. You can dive off into the deep, clear water below. There are also some underwater caves at this cenote. The water is cool, clear, and inviting. Jumping off this platform is awesome.

This is the Gran Cenote. It is also in Tulum, Mexico. It is a popular snorkelling spot. You can see some little fish and turtles as you swim around. There are also places to sit, walk, and eat. It gets very busy here, but you can find quiet spots, too.

Sinkholes are interesting, unique, scary, and wonderful. Which kind of sinkhole would you like to see the most?