Ice Balloon: Doomed Arctic expedition to the north pole
In 1897, a Swedish explorer named SA Andree attempted to be the first man to reach the north pole.
Unusually, instead of travelling by boat or a sled pulled by dogs, he opted to travel across hundreds of miles of Arctic ice by hydrogen balloon.
The expedition did not go well. Andree did not reach the pole.
In fact, neither he or his two colleagues ever returned home.
Using the expedition's diaries and photographs - dramatically recovered in the ice 33 years later - Alec Wilkinson's Ice Balloon recounts an epic and ultimately doomed tale of Arctic adventure. He spoke to the BBC about his book.
Photographs courtesy the Grenna Museum, Sweden/The Swedish Society for Anthropology and Geography