Korneyev's photo of the Elephant's Foot (1996), a large mass of corium and other materials formed underneath the Chernobyl Nuclear Plant during the disaster of 1986. Discovered in December of that year - still extremely radioactive, though the danger has decreased over time from decaying components.
Hardtack Umbrella underwater nuclear test in the Pacific Ocean near Bikini Atoll. The blast yield of the nuclear device was measured to be 8 kilotons of TNT. The spray dome resulting from the Umbrella blast reached about 5,000 ft (1,500 m) in height, and created a crater 3,000 ft (910 m) in diameter