The man, who is from Tamil Nadu and working in Car Nicobar, climbed a tree when the killer waves lashed the island on December 26.
He did not get down from the tree for ten days out of fear, Dr C B Sathaye, who treated him, said.
The doctor, who was a member of the 12-member medical team sent by Maharashtra Government to this island, said Defence personnel spotted him yesterday lying on the ground with severe dehydration.