Impressive images of these alien-like creatures were captured underwater – photographer Cai Songda is a keen diver and did not miss the chance to snap pictures of the unique “aliens”. Here: A Tremoctopus Gracilis in the waters around Anilao, Philippines. (Photo by Cai Songda/Caters News Agency)

A dog jumps into a swimming pool to retrieve a ball during the Chatsworth House Country Fair near Edensor, Britain on August 31, 2018. (Photo by Darren Staples/Reuters)

South Asian countries in terms of total contribution of travel and tourism to GDP. #6. Vietnam, Total GDP: USD 202.6 billion (2016). Contribution of Travel and Tourism to GDP: 9.1% . Here: A boat in the Thu Bon River, Hoi An, Vietnam. (Photo by Domingo Leiva/Getty Images)

Under Exposed: Pekka Tuuri (Finland) – Great white shark, Isla Guadalupe, Mexico. “Isla Guadalupe is the world capital when it comes to observing great white sharks, but cage diving seriously limits the possibilities to take ‘fresh’ pictures. When I took this, the water close to the surface was quite milky, making photography very challenging. From out of the “mist”, I saw this great white shark lurking behind a school of fusiliers. I quickly focused on the shark and set a wide aperture to get focus blur on the fish, along with a fast shutter to avoid excessive motion blur”. (Photo by Pekka Tuuri/The Outdoor Photographer of the Year/The Guardian)

These Northern Lights “rainbows” have turned the sky greener than the Earth below. Vitaly Istomin, 26, spent several nights in freezing conditions under the stars in northern Russia’s Khibiny Mountains to capture the aurora’s “rainbows”. (Photo by Vitaly Istomin/Caters News Agency)

A local boy plays football on Iracema Beach on June 11, 2014 in Fortaleza, Brazil. (Photo by Robert Cianflone/Getty Images)

Mount Sinabung volcano erupts, as seen from Tiga Pancur village, Karo Regency in Indonesia's North Sumatra province, in this October 8, 2014 file photo. (Photo by Y. T. Haryono/Reuters)

Elementary school sumo wrestlers compete in the sumo ring during the Wanpaku sumo-wrestling tournament in Tokyo, Japan July 30, 2017. (Photo by Kim Kyung-Hoon/Reuters)