Daigo Fukuryū Maru (第五福龍丸, Daigo Fukuryū Maru? Lucky Dragon 5) was a Japanese tuna fishing boat, which was exposed to and contaminated by nuclear fallout from the United States' Castle Bravo thermonuclear device test on Bikini Atoll, on March 1, 1954.
Kuboyama Aikichi, the boat's chief radioman, died a half a year later, on September 23, 1954, suffering from acute radiation syndrome. He is considered the first victim of the hydrogen bomb.
The Daigo Fukuryū Maru was saved in 1976 and is now on display in Tokyo at the Tokyo Metropolitan Daigo Fukuryū Maru Exhibition Hall.