There is a youtube of this with the picture reversed. Here are some of the comments.
dulakhc
dulakhc1 hour ago
It's a detonation alright..
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Todd Cameron
Todd Cameron6 hours ago
I don't think this is Lightning. There's lots of videos of lightning striking water that doesn't have anywhere near this effect. Really cool though whatever it is.
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Jimmy DaSquid
Jimmy DaSquid12 hours ago
Det cord.
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Patrick Teague
Patrick Teague18 hours ago
http://www.snopes.com/lightning-striking-a-river/
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Karynne Williams
Karynne Williams21 hours ago
Does not look like lightning to me. and why is it backwards? It looks like detonation cord running down a hill to an explosive in the water. Just sayin.
Reply 5