Only 15% of the surface of the Earth is not water, desert, ice or mountain. For humans, a tropical, low altitude, air-breathing animal, this means most of the planet represents a hostile or extreme environment. Extreme environmental physiology covers a wide range of topics including: physiologically preparing groups such as elite athletes to try and maintain high level performance in hot and cold environments, using strategies such as acclimatisation; considering using altitude training and heat acclimation as ergogenic aids to enhance performance in temperate sea level conditions; determining the benefit of cross-adaptation between one extreme environment and another; protecting, via technological solutions (e.g. personal protective equipment), those who, as part of their work or play, enter extreme environments (e.g. astronauts, divers, firefighters, sailors, the military). Our habitation of the planet has been largely enabled by technological advances (clothing, shelter, heating) founded on intellect. But sometimes this technology goes wrong requiring extreme environmental research related to accidental exposures and the consequent pathophysiology of heat illness, cold injury, hypothermia; hypoxia, barotrauma and drowning. These are not just “niche issues”; forty-three people around the globe drown each hour. These are mostly young people and this figure is an under-estimation. Finally, research in extreme environments such as microgravity and hypoxia is also shedding new light on areas such as ageing, body tissue wasting and outcome in critical illness. If any of the above interests you, let’s chat on the 19th December 4-6pm (GMT).