Students pose for a picture with a 3- D optical illusion artwork of a devastated cityscape in Aleppo, Syria at the campus of the Meiji University in Tokyo on November 18, 2016. The Japanese branch of the human rights organisation Amnesty International displayed the artwork to encourage people to think about the Syrian civil war. (Photo by Toshifumi Kitamura/AFP Photo)

A tourist clad in Japanese kimono takes a picture in front of s portrait shop in Tokyo's Asakusa district, Thursday, February 15, 2018. Asakusa is a popular district four tourists in the capital. (Photo by Shizuo Kambayashi/AP Photo)

A family wearing traditional Japanese clothing posed for a photograph during spring season in one of the garden in Kiyomizu dera, Kyoto prefecture, Japan on March 30, 2018. (Photo by Richard Atrero de Guzman/NurPhoto via Getty Images)

A model presents creations from the 2023 Spring/Summer collection by Japanese designer Lim Asafuji for the label “pays des fees” during the Tokyo Fashion Week in Tokyo, Japan, 01 September 2022. The presentation of the 2023 Spring/Summer collections runs from 29 August to 03 September. (Photo by Franck Robichon/EPA/EFE)

Belgian-Dutch racing driver Maz Verstappen was racing for Red Bull at the Japanese Grand Prix in Suzuka at Suzuka International Circuit on October 9, 2022 when a spider on the camera lens threatened to get in the way of the action. (Photo by DPPI)

Japanese actresses Ami Suzuki and Aya Suzuki pose before Dries Van Noten Spring/Summer 2024 Women's ready-to-wear collection show during Paris Fashion Week in Paris, France on September 27, 2023. (Photo by Johanna Geron/Reuters)

Located in Kunshan, eastern China, the restaurant relies on over a dozen machines for tasks such as greeting customers, waiting on tables and cooking basic meals. The eatery becomes the third café in the world to rely on the use of robot employees, potentially giving a glimpse into how future businesses could operate. Photo: This photo taken on August 13, 2014, shows a robot carrying food to customers in a restaurant in Kunshan. It's more teatime than Terminator – a restaurant in China is electrifying customers by using more than a dozen robots to cook and deliver food. (Photo by Johannes Eisele/AFP Photo)

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.