Urban spelunker

Urban exploration (often shortened as urbex, UE, bexing, urbexing and sometimes known as 'roof-and-tunnel hacking') is the exploration of man-made structures, usually abandoned ruins or not usually seen components of the man-made environment. Photography and historical interest/documentation are heavily featured in the hobby and, although it may sometimes involve trespassing onto private property, this is not always the case. Informally named "urbexing," the popular activity is engaged with by people of all ages, even the elderly. Urbexing (or urban exploration may also be referred to as draining (an alternate form of urbexing where drains are explored), urban spelunking, urban rock climbing, urban caving, or building hacking.

The nature of this activity presents various risks, including both physical danger and the possibility of arrest and punishment. Some activities associated with urban exploration may violate local or regional laws and certain broadly interpreted anti-terrorism laws or be considered trespassing or invasion of privacy.

Ventures into abandoned structures are perhaps the most common example of urban exploration. At times, sites are entered first by locals and may suffer from large amounts of graffiti and other acts of vandalism. Although targets of exploration vary from one country to another, high-profile abandonments include amusement parks, grain elevators, factories, power plants, missile silos, fallout shelters, hospitals, asylums, schools, poor houses, and sanatoriums.

In Japan, abandoned infrastructure is known as haikyo (廃虚^?) (literally "ruins"), but the term is synonymous with the practice of urban exploration.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.

...
Wikipedia