Hang Én ('swift cave' in Vietnamese, named for the birds that nest in it[1]), occasionally referred to as Én cave in English, is a cave in Phong Nha-Ke Bang National Park, a UNESCO World Heritage Site.

The cave, which goes through a mountain for 1,645 metres (5,397 ft), has a maximum height around 100 metres (330 ft), and a maximum width of approximately 170 metres (560 ft) is a feeder to Hang Sơn Đoòng, 2 kilometres (1.2 mi) away.

The only ways to reach the cave are by helicopter, or an approximately four-hour jungle trek from the nearest road.

Both Én and Sơn Đoòng were featured in footage aired on the television program Good Morning America in May 2015,[3][4] dubbed one of "the top 10 cultural events of the year" in Vietnam by Viet Nam News.

[5] Hang Én was selected by the US-based Warner Bros. as a shooting location for the 2015 film Pan.