His father died in a traffic accident when he was six years old, and after that Danielsson grew up in Norrköping with his mother and aunt, who both encouraged his adventuring ambitions.

His doctoral thesis on the Tuamotus island chain, submitted to Uppsala University in 1955, was published the following year as Work and Life on Raroia.

[5] He subsequently wrote many books and scripted many films, becoming one of the world's foremost students of Polynesia.

He and his wife were particularly outspoken critics of French nuclear tests at Moruroa and Fangataufa atolls, and of the destruction of Polynesian culture through colonialism.

[7] Bengt died in July 1997 following a deterioration in his health,[8] and was buried at Östra Tollstad Church in Mjölby Municipality, Sweden.