high-voltage cabling or by microwave radiation from roof-mounted equipment. In addition, laboratory buildings often vent hazardous gasses through exhaust stacks on the roof. Tunnels can be extremely dangerous — superheated steam pipes are not always completely insulated; when they are insulated, it is occasionally with carcinogenic materials like asbestos. Opening or damaging a steam valve or pipe can be potentially deadly. Steam contains significantly more thermal energy than boiling water, and transfers that energy when it condenses on solid objects such as skin. It is typically provided under high pressure, meaning that comparatively minor pipe damage can fill a tunnel with steam quickly. In 2008, a high-pressure steam pipe exploded in the subbasement of Building 66 at MIT, apparently due to a construction defect. The explosion and ensuing flood caused extensive damage and lethal conditions in the subbasement. Confined spaces contain a range of hazards — from toxic gases like hydrogen sulfide and carbon monoxide, to structures that may flood or entrap an adventurer. An explorer who enters a tunnel via a lock bypass method or via an inadvertently-left-open door may find themself trapped if the door locks behind them — quite possibly in an area with no cell phone reception, and no one within earshot. See also Columbia University tunnels Elevator surfing Hacks at the Massachusetts Institute of Technology Hacker (term) Rooftopping Urban exploration References External links MIT hacks site; deals primarily with pranks, some of which involve a roof hacking component Infiltration.org page on college tunnels A link to urban exploring at the University of Virginia. Contains map of steam tunnels Daily Princetonian article on a student injured in a fall while exploring a tower in the University's chapel UCSDSecrets, an introductory blog about UCSD. including its tunnels Institute Historian, T. F. Peterson, Nightwork: A History of Hacks and Pranks at MIT (revised edition), MIT Press, Cambridge, Massachusetts. 2011. — Extensive documentation, many photographs, special essays "Abandon Hope, Part 1" and "Abandon Hope, Part 2", a two-part article on the Columbia University tunnels Types of climbing Urban exploration Subterranea (geography)