“Hippo Chase”. As we approached the camp the Selinda Reserve of northern Botswana our boat passed by a hippo resting in the water. I turned around to look back at the boat's wake and saw the hippo charging after us! The hippo must've been tired from an all-nighter because he was angry. He rose way up out of the water three times trying to chase our boat! He was coming at us with such force that he created a wake of his own. Photo location: Selinda Reserve of northern Botswana. (Photo and caption by Curtis Simmons/National Geographic Photo Contest)

Bosnian men urge their horses to pull logs up a hill during a competition in the Bosnian town of Sokolac 50 kms west of Sarajevo, Bosnia,on Monday, April, 13, 2015. The annual festival celebrates the centuries old tradition of pulling logs honoring the owners of the strongest horses. Owners of the horses gather from all over Bosnia and beyond, and compete in a show of horse strength. (Photo by Amel Emric/AP Photo)

Erotic members-only club Snctm in Los Angeles, California, USA on January 28, 2017. A masqued black-tie dinner that evolves over the course of the night from amuse bouche to what founder, Damon Lawner, calls “erotic theater”, where female performers. Some guests engage, some engage only with each other (while women can buy a ticket, men cannot attend unless they’re members ($10,000-$50,000), part of a couple, or reserve dinner), and others choose not to touch at all. The monthly event at a Holmby Hills mansion is not a sеx or swingers party, but instead is about exploring the boundaries of what sеx means, and how it inherently makes us all feel. (Photo by Elizabeth Lippman)

Fabrice Monteiro travelled to the most polluted places in Africa and created terrifying characters who roamed their midst dressed in eerie debris. They are spirits, he says, on a mission to make humans change their ways. Informed by Africa’s environmental problems, Fabrice Monteiro’s photographs aim to highlight urgent ecological issues all over the world. His series “The Prophecy” is on show at Photo Basel 2017 until 18 June. (Photo by Fabrice Monteiro/Photo Basel 2017/Mariane Ibrahim Gallery/The Guardian)

The winner of the Miss Tattoo Brazil 2014 contest, Bruna Barros, shows a tattoo that says 'My body, my rules' during Tattoo Week, the largest convention of art in the skin of Latin America, in Sao Paulo, Brazil, 14 July 2017. A tattooed woman beauty pageant, the new trends and techniques of the tattoo world, body piercing and the environment of the art of definitively painting the body, are all due to be addressed during the seventh edition of the “Tattoo Week Sao Paulo“. (Photo by Sebastiao Moreira/EPA)

Masks that come with T'antawawas bread are displayed in a popular market of La Paz, October 27, 2015. Residents of La Paz city have started to prepare offerings for their dead relatives next Sunday as part of the All Saints' Day celebrations. The offerings include things the deceased liked during their life, such as fruits, food, breads and drinks, according to local media. (Photo by David Mercado/Reuters)

An Egyptian army soldier stands guard near debris from a Russian airliner which crashed at the Hassana area in Arish city, north Egypt, November 1, 2015. Russia has grounded Airbus A321 jets flown by the Kogalymavia airline, Interfax news agency reported on Sunday, after one of its fleet crashed in Egypt's Sinai Peninsula, killing all 224 people on board. (Photo by Mohamed Abd El Ghany/Reuters)

A street vendor spreads vermilion powder used for worship during the Tihar festival, also called Diwali in Kathmandu, Nepal, November 9, 2015. Hindus all over Nepal are celebrating the Tihar festival during which they worship cows, which are considered a maternal figure, and other animals. Also known as the festival of lights, devotees also worship the goddess of wealth Laxmi by illuminating and decorating their homes using garlands, oil lamps, candles and colourful light bulbs. (Photo by Navesh Chitrakar/Reuters)