People swim underwater at Clovelly Beach on December 14, 2023 in Sydney, Australia. A severe heat wave hit Sydney over the weekend, a precursor of hot and dry conditions expected for the rest of the summer which will also bring heightened bushfire risk. The mercury rose to alarming levels again on Thursday. (Photo by Jenny Evans/Getty Images)

NASA astronauts Stan Love and Loral O’Hara test Axiom Space’s lunar spacesuits underwater on October 1, 2025. The AxEMU suit is designed for the Artemis III mission to the moon’s south pole, due to lift off no earlier than mid-2027. (Photo by NBL/NASA via South West News Service)

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)

A diver wearing a Santa Claus costume swims with fishes in a large tank during an underwater performance for the upcoming Christmas celebration at Hakkeijima Sea Paradise in Yokohama, south of Tokyo, Japan on December 1, 2022. (Photo by Kim Kyung-Hoon/Reuters)

“Alice in Waterland” is a beautiful series of photographs re-imagining the Lewis Carroll classic underwater. It’s a creation of photographer Elena Kalis, who lives on a small island in The Bahamas, surrounded, she says, “by pristine clear warm water. Underwater is where I spend a lot of time; snorkeling, diving, photographing. It is fascinating how the world changes down below: light, sound, gravity and proportions are different from what we are used to”. (Photo by Elena Kalis)

A girl watches as Saen Dao, an eight-year-old female asian elephant, and her mahout perform underwater during a show at the Khao Kheow Open Zoo in Chonburi south of Bangkok on June 1, 2017. (Photo by Roberto Schmidt/AFP Photo)

This picture taken with an underwater camera shows Japan' s Yumi Adachi competing in the Mixed Duet technical final during the synchronised swimming competition at the 2017 FINA World Championships in Budapest, on July 17, 2017. (Photo by Bernadett Szabo/Reuters)