When the 2004 tsunami struck coasts along the Indian Ocean, it was not a sixth sense that made elephants run for the hills, often carrying unsuspecting tourists on their backs to safety. It was because they heard the tsunami coming.
A tsunami is a very long water wave, its wavelength hundreds of miles long in the deep ocean. But in shallow water near land the wavelength shortens. The tsunami waves produce waves in the atmosphere of the same wavelength, which happens to be the wavelength of very low-frequency sound (called infra-sound).
It is too low in frequency for humans to hear, but the elephants can hear these sound waves. And in 2004 when they heard a thundering roar coming from the sea, they ran the other way as fast as they could. Anyone for establishing an Elephant Tsunami Warning System? For more Ocean facts check out Dr. Bruce Parker's book: The Power of the Sea