These adventurers are illegally BASE jumping from the famous Half Dome cliff in Yosemite National Park, California. BASE stands for buildings, antennas, spans (bridges), and Earth (mountains and cliffs like this one).

Photograph by Jimmy Chin and Linsey Dyer, National Geographic
  • On January 18, 1981, two adventurers, Phil Smith and Phil Mayfield, parachuted from the top of a skyscraper in Houston, Texas. With this jump, they became the world’s first BASE jumpers—the first people to successfully jump from all four of the extreme sport’s namesake structures—buildings, antennas, spans, and the Earth. 
    BASE jumping only gained a name in the 1970s, but daredevils have been using parachutes to jump off tall structures for much longer. In 1966, skydivers jumped off the famous peak of El Capitan in Yosemite National Park, California. (Cliffs and mountains are the “Earth” in BASE jumping.) Today, BASE jumpers have plummeted from the Burj Khalifa, the tallest building in the world; an antenna tower near Chernobyl, Ukraine, nicknamed the “Russian Woodpecker”; the Sydney Harbor Bridge (a “span”) in Sydney, Australia; and even a peak in the Andes, Cerro El Plomo, Chile.
    BASE jumping is incredibly dangerous and often illegal. One study, conducted in 2002, found that one of every 60 BASE jumpers died as a result of the jump. The National Park Service briefly issued permits for BASE jumping from places such as El Capitan, but banned the practice after less than a year. Jumping from buildings, antenna towers, and bridges (spans) is usually prohibited, because of the financial and physical danger to nearby residents, workers, or commuters. 
  • Term Part of Speech Definition Encyclopedic Entry
    adventure Noun

    exciting or unusual experience.

    antenna Noun

    structure through which electromagnetic signals are received.

    ban Verb

    to prohibit, or not allow.

    cliff Noun

    steep wall of rock, earth, or ice.

    Encyclopedic Entry: cliff
    commuter Noun

    person who travels between home and work.

    daredevil Noun

    reckless or daring person.

    extreme sport Noun

    non-traditional athletics that are often considered dangerous.

    financial Adjective

    having to do with money.

    illegal Adjective

    forbidden by law.

    parachute Noun

    device which allows a person to glide down safely from a great elevation.

    peak Noun

    the very top.

    permit Noun

    official, written permission to do something. Sometimes called a license.

    plummet Verb

    to fall sharply.

    prohibit Verb

    to disallow or prevent.

    resident Noun

    person who lives in a specific place.

    skyscraper Noun

    very tall building.

    structure Noun

    system of organization.