A squid swims underwater off the shore of the coastal city of Qalamun, north of the Lebanese capital Beirut, on September 24, 2019. (Photo by Ibrahim Chalhoub/AFP Photo)

Tourists pose for a selfie in Cancun, October 13, 2015. Cancun's transformation in the 1970s from a small Caribbean fishing village into a strip of nightclubs and high-rise hotels has reduced biodiversity and polluted water resources as infrastructure struggles to keep up. (Photo by Edgard Garrido/Reuters)

A huge colony of Pacific Walrus on Arakamchechen Island in the Northern Bering Sea. (Photo by Francois Gohier/Ardea/Caters News)

Festival goers participate in a dance class on embracing kinetic intimacy in the dance shala a the Oregon Eclipse Festival, August 20, 2017, at Big Summit Prairie ranch in Oregon' s Ochoco National Forest near the city of Mitchell ahead of the total solar eclipse on August 21, 2017. (Photo by Robyn Beck/AFP Photo)

Cave Diver, Anhumas Abyss, Bonito, Brazil: The Anhumas Abyss is an underground cavern with a crystal-clear lake below, more than 260 feet (79 m) deep. A visitor must enter through a narrow opening at the top of the chamber and rappel into the cave. Snorkeling and scuba diving in the lake reveal amazing scenery. Distinctive, conical limestone stalagmites and stalactites occupy the lake and the surrounding area, some reaching 65 feet (20 m) high. (Photo by Marcio Cabral/Nature’s Best Photography Awards 2017)

A new book published by the UK Natural History Museum showcases some of the most memorable underwater photographs taken over the last few decades in its annual wildlife photographer of the year competition. Here: Giant gathering by Tony Wu. “The first indication that something extraordinary was going on were the blows, huge numbers of them – the exhalations of huge numbers of whales. Entering the water, the photographer witnessed an extraordinary scene”. (Photo by Tony Wu/Unforgettable Underwater Photography/NHM)

“Thor Heyerdahl (October 6, 1914, Larvik, Norway – April 18, 2002, Colla Micheri, Italy) was a Norwegian ethnographer and adventurer with a background in zoology and geography. He became notable for his Kon-Tiki expedition, in which he sailed 8,000 km (4,300 miles) by raft from South America to the Tuamotu Islands. All his expeditions are shown in the Kon-Tiki Museum, Oslo”. – Wikipedia

Photo: Norwegian anthropologist Thor Heyerdahl with a model of the balsa raft “Kon-Tiki” on which he drifted 4,300 miles from Peru to the Tuamotu Islands, proving his theory that Polynesia could originally have been populated by South Americans. (Photo by Express/Express/Getty Images). 1950

This November 8, 2019, photo provided by John Guillote shows a view from the main lab of the Sikuliaq in the Chukchi Sea. University of Washington scientists onboard the research vessel are studying the changes and how less sea ice will affect coastlines, which already are vulnerable to erosion because increased waves delivered by storms. More erosion would increase the chance of winter flooding in villages and danger to hunters in small boats. (Photo by John Guillote via AP Photo)