Urban exploration
[7] Haikyo are particularly common in Japan because of its rapid industrialization (e.g., Hashima Island), damage during World War II, the 1980s real estate bubble, and the 2011 Tōhoku earthquake and tsunami.
[8] In Bosnia and Herzegovina, a large underground facility abandoned since 1992 is Željava Air Base, situated under the Gola Plješevica mountain, near the city of Bihać.
Nowadays, it is popular for urban exploration, although it is risky due to the possibility of anti-personnel landmines being located in unexplored areas, remnants from 1990s Bosnian War.
Some consider the Mines of Paris, comprising many of the tunnels that are not open to public tours, including the catacombs, the "Holy Grail" due to their extensive nature and history.
Sewers are among the most dangerous locations to explore owing to the risk of poisoning by buildups of toxic gas (commonly methane, hydrogen sulfide, or carbon dioxide).
[14] Exploring active and abandoned subway and railway tunnels, bores, and stations is often considered trespassing and can result in civil prosecution due to security concerns.
Experienced explorers are very cautious inside active utility tunnels since pipes can spew boiling hot water or steam from leaky valves or pressure relief blow-offs.
Steam tunnels have generally been secured more heavily in recent years due to their frequent use for carrying communications network backbone cables, increased safety and liability concerns, and perceived risk of use in terrorist activities.
Recent television shows such as Urban Explorers on the Discovery Channel, MTV's Fear, and the Ghost Hunting exploits of The Atlantic Paranormal Society have packaged the hobby for a popular audience.
The fictional film After... (2006), a hallucinatory thriller set in Moscow's underground subways, features urban explorers caught up in extreme situations.
Talks and exhibits on urban exploration have appeared at the fifth and sixth Hackers on Planet Earth Conference, complementing numerous newspaper articles and interviews.
[19] In Australia, lawyers for the Roads and Traffic Authority of New South Wales shut down the Sydney Cave Clan's website after they raised concerns that the portal could "risk human safety and threaten the security of its infrastructure".
[19] Another website belonging to the Bangor Explorers Guild was criticized by the Maine State Police for encouraging behavior that "could get someone hurt or killed".
Some abandoned locations may be heavily guarded by motion detectors and active security patrols, while others are more easily accessible and carry less risk of discovery.
