A man wearing an illuminated atmospheric diving suit as part of an installation titled “What Lies Beneath” looks at members of the public during the Vivid Sydney festival of light and sound in Sydney, Australia, May 26, 2017. (Photo by Steven Saphore/Reuters)

Doesn’t taking a nap in a hammock outdoors sound lovely? Perhaps not when you’re hanging in the air, thousands of feet above ground, between two mountains in the Italian Alps! Which is exactly what these adventurous folks did during the International Highline Meeting in Monte Piana, Italy. (Photo by Sebastian Wahlhuetter Photography)

An F/A-18 Hornet assigned to Strike Fighter Squadron One Five One (VFA-151) emerges from a cloud created when it broke the sound barrier in the skies over the Pacific Ocean, July 7, 1999. (Photo by John Gay/US Navy)

Radio City Music Hall Rockettes perform after days of rehearsal and routine polished to perfection at the Radio City Music Hall in New York City on July 26, 1949. (Photo by Ivan Dmitri/Getty Images)

Bici Palermo Tuning – a group of teenagers from the Sicilian capital Palermo – spend anything up to €1,300 customising their bikes with car batteries and multiple speakers to develop thunderous sound systems. The police are not impressed. (Photo by Matteo de Mayda/Cosimo Bizzari/The Guardian)

A woman waits to hear about her sister, a teacher, following a shooting at the Sandy Hook Elementary School in Newtown, Connecticut. A man killed his mother at their home and then opened fire inside the elementary school where she taught, massacring 26 people, including 20 children, as youngsters cowered in fear to the sound of gunshots reverberating through the building and screams echoing over the intercom. (Photo by Jessica Hill/Associated Press)