The vast, teeming Amazon rain forest can kill you in all sorts of ways, from encounters with ravenous piranhas to suspicious native tribes. But the most lethal terror reputed to be lurking in these parts is the giant anaconda, a lightning-quick snake more than 30 ft. (9 m) long, capable of capsizing and crushing wooden boats floating down the Amazon. Scientists believe that such a monstrous version of the anaconda — which in real life rarely grows beyond an already scary 17 ft. (about 5 m) — no longer exists, though that hasn't deterred generations of explorers. Even U.S. President Teddy Roosevelt put a bounty of $50,000 — a kingly sum in his time — on the skin of the first giant anaconda brought to the Bronx Zoo, which was then run by one of Roosevelt's close friends. That prize went uncollected, though the famous British adventurer Percy Fawcett claimed he spotted one in 1907 but apparently didn't have the means to overcome it and retrieve it. He disappeared during a later expedition in the Brazilian jungle, never to be heard from again.