Every year, millions of people visit America’s national parks . Some seek recreation, others tranquillity. But a few seek the chance to fly.

Depending on who you ask, base jumping is either an extreme sport or a pursuit of artistic and emotional expression. While skydivers launch themselves from planes, the acronym for base jumping stands for leaps from a building, antenna, span or earth. The last category covers cliff faces in land managed by the National Park Service (NPS).

In some cases, including an incident at the Grand Canyon this month, botched jumps can be fatal. NPS for decades has banned the activity, which can incur heavy fines or jail time, but that hasn’t stopped people from going to parks with parachutes and wingsuits and leaping off some of the most iconic rock slabs in the country. In recent years, a group of base-jumping advocates have been lobbying to decriminalise it, arguing the Park Service unfairly singles out their sport — and, in doing so, makes the potentially fatal activity more dangerous.

“We obviously like the jump and the flight, but we also really like just hanging out in the mountains and the beauty and seeing the people,” said Todd Shoebotham, a veteran base jumper and a member of the advocacy group Base Access. At 57, Shoebotham has been jumping for decades and now manufactures base-jumping equipment. “To think that we have some kind of death wish is just so wrong,” he said.

To the public, however, base jumping tends to make head.