What strength saved 3 men adrift at sea for 2 days in Vietnam?

In a story that has moved the entire nation, three fishermen from Ly Son Special Zone in Quang Ngai Province, central Vietnam miraculously survived after drifting nearly 100 kilometers for two days through the fury of storm Kalmaegi, with 37-year-old Le Van Sanh swimming for 24 hours without a life jacket, driven only by his will to live and thoughts of his wife and children.