A cenote is a natural phenomenon, a sinkhole in the Earth’s surface. The Yucatan Peninsula in Mexico has an estimated 7,000 cenotes because it is primarily made up of porous limestone. For millions of years, rainfall slowly ate away at the limestone and a huge system of underground caves and caverns was formed. Many filled with water from rain or from the underground water table. When the roof of a water filled cave collapses, a cenote is born. The water found in a cenote may be fresh water, salt water, or both. Structurally it may be completely open, like a lake, almost completely closed with just a small opening at the top, or somewhere in between.

To an outsider, their passion is at times illegal and often on the verge of life and death. But climbing rooftops of high-rise buildings and exploring abandoned facilities is in the blood of these young Muscovites. The small group calls itself “Rudex”, which stands for “roof and decay exploration”, and is akin a Western youth craze known as urbex or “urban exploration” of man-made structures. Here: Urban explorer Vad Him of Rudex team jumps whilst on a rooftop in Moscow, Russia, August 14, 2017. (Photo by Maxim Shemetov/Reuters)

Artist Gaelle Villedary has installed a grass “carpet” across the village of Jaujac in France to celebrate the 10th anniversary of the Arts and Nature Trail program. The green trail is made of 168 rolls of grass and runs for 1,377 feet (420 metres) to connect the village seamlessly to its surrounding natural landscape.

A man inspects a plastic cover placed over an artwork attributed to Banksy on May 17, 2012 in London, England. The stencilled image depicts a poor child making Union Jack flags on a sewing machine and is located on the wall of a Poundland discount shop in the Wood Green area of north London. (Photo by Peter Macdiarmid)

The groom Paul Bellas and bride Heidi Coxshall will have a distinctive Shrek wedding. Few brides are willing to show themselves with green painting! The wedding is just because their 4-year-old son loves the movie Shrek, who’ll be a guest donkey on the wedding. The relatives and friends of the newlyweds are all dressed as roles in the Disney movie, such wedding is absolutely unique!

These stunning pictures of beautiful Icelandic waterfalls will take your breath away. The mesmerizing shots show the striking waterfalls set against the night sky and the hypnotic green glow of the northern lights, as well as the picturesque Icelandic scenery and stunning sunrises. Here: A mesmerising waterfall in the Icelandic country-side. (Photo by Arnar Kristjansson/Caters News)

Neil Zeller's snaps were taken across Canada, where he photographs the northern lights dancing across a dark night sky. In one stunning shot, Zeller, 42, even manages to capture a flash of lightning beneath a storm cell while an aurora gives off a magnificent green glow. The photographer, from Calgary, Alberta, describes himself as a night person, and became interested in night photography about 10 years ago. (Photo by Neil Zeller/Caters News)