Teeming with images of spectacular underwater scenes from around the world, Call of the Blue is the culmination of a five-year project by the photographer and ocean conservationist Philip Hamilton. This groundbreaking book includes contributions from acclaimed scientists and ocean “guardians”, who reveal what drove them to answer the call of the blue. (Photo by Philip Hamilton/The Guardian)

Bride Duangreuthai Amnuayweroj and groom Kasemsak Jiranantiporn fly while attached to cables during a wedding ceremony ahead of Valentine's Day at a resort in Ratchaburi province, Thailand, February 13, 2016. Four Thai couples took part in the wedding ceremony arranged by the resort. (Photo by Athit Perawongmetha/Reuters)

A Chinese couple take pictures in an interactive installation art work named “You and Me” on Valentine's Day at 798 Art Zone on February 14, 2012 in Beijing, China. (Photo by Feng Li/Getty Images)

Couples (L-R) Chaiyut Phuangphoeksuk and Prontathourn Pronnapatthun, and Nichapatr Koomsombut and Pirat Rungthongoran run from sheep during their wedding ceremony at a resort in Ratchaburi province February 13, 2015. Three Thai couples took part in the wedding ceremony arranged by a resort themed around fun activities ahead of Valentine's Day. (Photo by Athit Perawongmetha/Reuters)

Stefan Libon proposes to girlfirend Jess McGarrity in front of a banner message “Marry Me Jess?” on the deck of the Queen Mary 2, at Mrs Macquarie's Chair on Valentines day, February 14, 2012 in Sydney, Australia. (Photo by James Morgan/Carnival Australia via Getty Images)

A general view of the residential area is pictured during dusk at Jodhpur in Rajasthan, April 5, 2015. Jodhpur, also known as the blue city in the desert Indian state of Rajasthan, which residents say originally, was used to show where the highest caste of priestly Hindus live, who wanted to set them apart from the rest of the population. Later the rest of the population followed suit. Another reason for the city to be blue is to keep the buildings cool during the summers, local residents said. (Photo by Adnan Abidi/Reuters)

A large stainless steel shovel lies on top of steamed crabs at the A.E. Phillips & Son Inc. crab picking house on Hooper's Island in Fishing Creek, Maryland August 26, 2015. Workers speed through the lump and back fin meat inside the crabs while leaving the more tedious task of picking the claws to others. (Photo by Jonathan Ernst/Reuters)