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.

We received intriguing letter: “Hello! My name is Glenda Lissette, I am an 18 year old photographer from Chicago, IL. I produce surreal and conceptual photographs. I am currently working on a project where I take a photo a day for an entire year”. Well, let's look!

Photo: “If I Only Had a Brain” (365 project). (Photo by Glenda Lissette)

“I bought my first dlsr camera in 2009 may. The first part of my life is gone but the other i dedicate to photography. If i try to imagine myself, i saw someone on the road, who walking straight to the light. This kind of light is the photography and the post-processing in my life. My pictures express the feelings, moods what i felt under my trip in the last few years”. – Ildiko Neer

Photo: “Path to the shine”, 2011. (Photo by Ildiko Neer)

In this photo distributed by the Israeli Defense Forces (IDF) May 23, 2005, woman soldiers wear branches in their helmets as their infantry instructors' course learns about camouflage during the field craft week of their training May 19, 2005 at an army base near Beersheva in Israel's southern desert. It takes the IDF more than 2 months to teach these 18-year-old female recruits the basic arts of warfare before they assigned to pass on their newly-acquired skills to the army's male and female draftees. (Photo by Abir Sultan/IDF via Getty Images)

The public get the first view at the opening of the new miniature model Knuffingen Aiport at Miniatur Wunderland on the airport's opening day on May 4, 2011 in Hamburg, Germany. Miniatur Wunderland is the world's largest model railroad landscape, and the model airport, also the world’s largest, goes into operation following 6 years of development and construction and an investment of EUR 3.5 million. The airport is a reproduction of Hamburg’s international airport and includes 40 aircraft that take off and land and 90 vehicles that autonomously move around the runways on May 4, 2011 in Hamburg, Germany. (Photo by Stuart Franklin/Getty Images)

South Korean bee farmer Ahn Sang-Kyu protests Japan's claim of sovereignty over disputed islets May 2, 2006 in Seoul, South Korea. Ahn, a local bee farmer, released over 140,000 bees and attracted them to his body to protest Japan's sovereignty claims over a tiny group of islands located off the east coast of South Korea, called the Dokdo islets by the Koreans and Takeshima by the Japanese. The volcanic islets located about 90 kilometres east of South Korea's Ullung Island, have been a source of diplomatic friction between South Korea and Japan for years. (Photo by Chung Sung-Jun/Getty Images)

Student, Shoukria positions a stone for cutting at the Turquoise Mountain Gem cutting class on May 18, 2011, in Kabul, Afghanistan. The mineral resources of Afghanistan are relatively unexplored even with Afghanistan's mineral wealth of coal, copper, gold and iron ore, with precious and semiprecious stones, including high-quality emerald, lapis lazuli, red garnet and ruby. Given the country's remote and rugged terrain, on-going instability plus an inadequate infrastructure and transportation means that mining is still difficult. While many are trying to bring positive changes, Afghanistan's mining industry uses unregulated, primitive methods and outdated equipment. (Photo by Paula Bronstein/Getty Images)

A black bull sarcophagus stands at Puri Ubud during the Hindu Royal cremation – also know as the Pengabenan – for the late Anak Agung Niang Rai, mother of Gianyar Regent, Tjokorda Oka Artha Ardana Sukawati, at Puri Ubud in Gianyar Bali on August 17, 2011 in Ubud, Bali, Indonesia. Niang Rai died in a Denpasar hospital in May; her actual cremation will take place on August 18 and will involve a nine level, 24m high 'bade' or body carring tower, made by upto 100 volunteers from 14 local villages. It will be carried to the cremation by 4500 Ubud residents. (Photo by Ulet Ifansasti/Getty Images)