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.

Gdańsk is a Polish city on the Baltic coast. The city's professional football club is Lechia Gdansk. Founded in 1945, they play in the Ekstraklasa, Poland's top division. The European Football Championship will take place in Gdansk 2012.

Photo by: Sludgegulper ; Source: Flickr

Potoos (family Nyctibiidae) are a group of near passerine birds related to the nightjars and frogmouths. They are sometimes called Poor-me-ones, after their haunting calls. There are seven species in one genus, Nyctibius, in tropical Central and South America.
These are nocturnal insectivores which lack the bristles around the mouth found in the true nightjars. They hunt from a perch like a shrike or flycatcher. During the day they perch upright on tree stumps, camouflaged to look like part of the stump. The single spotted egg is laid directly on the top of a stump.

Assistant Manager Jayesh Vaghela brushes a vintage silk top hat at Lock & Co. Hatters on March 22, 2011 in London, England. Founded in St. James's in 1676, when Charles II was on the throne, this family owned business has provided hats for Royalty and the gentry for over 300 years. Staff report that sales of formal hats are booming ahead of the wedding of Prince William and Kate Middleton in Westminster Abbey on April 29, 2011.

Three elephant seals put on a show in Roie Galitz's “Three Tanors”, taken on January 7, 2016 in South Georgia Island. The Comedy Wildlife Photography Awards are in full swing, so check out some of the fierce competitors jostling for the top prize this year. Photographers Paul Joynson-Hicks MBE and Tom Sullam founded the awards to spotlight wildlife conservation efforts and to inject some humour into the world of wildlife photography. (Photo by Roie Galitz/CWPA/Barcroft Images)

Kyaiktiyo, Burma, 1978. The Golden Rock at Shwe Pyi Daw (the Golden Country), the Buddhist holy place. Hiroji Kubota writes: “I was desperate to keep a distance from America for a while; luckily, I found Burma and its gentle and compassionate people. In the spring of 1978, on the top of the hill where I took this photo, I had two Leica bodies: the one with Tri-X and the other with Kodachrome 64. Soon after, I realised that the colour one looked very colourful and was more powerful. That was my decisive moment, to become a colour photographer”. (Photo by Hiroji Kubota/Magnum Photos)

A volunteer pets a tiger inside a cage at the Wat Pa Luang Ta Bua, otherwise known as Tiger Temple, in Kanchanaburi province February 12, 2015. Thai officials last week raided the Buddhist temple that is home to more than 100 tigers and are currently conducting an investigation into suspected links to wildlife trafficking. Authorities from Thailand's Department of National Parks, Wildlife and Plant Conservation on Thursday checked 143 Bengal tigers living at the temple, and found them to be in good health. (Photo by Athit Perawongmetha/Reuters)