On November 23, the Germaintercepted and struck the Ben Lomond with two torpedoes As the ship was sinking, Poon Lim took a life jacket and jumped overboard before the ship's boilers exploded.[3][4] As the ship sank in two minutes, 53 of the crew of 54 were lost including the master, 44 sailors and eight gunners, making Lim the sole survivor.[5][6]
After approximately two hours in the water, he found an 8" square wooden raft and climbed into it. The raft had several tins of biscuits, a forty litre jug of water, some chocolate, a bag of sugar lumps, some flares, two smoke pots and a flashlight.
Poon Lim initially kept himself alive by drinking the water and eating the food on the raft, but later resorted to fishing and catching rainwater in a canvas life jacket covering. He could not swim very well and often tied a rope from the boat to his wrist, in case he fell into the ocean. He took a wire from the flashlight and made it into a fishhook, and used hemp rope as a fishing line. He also dug a nail out of the boards on the wooden raft and bent it into a hook for larger fish. When he captured a fish, he would cut it open with a knife he fashioned out of a biscuit tin and dry it on a hemp line over the raft. Once, a large storm hit and spoiled his fish and fouled his water. Poon, barely alive, caught a bird and drank its blood to survive.
When he saw sharks, he did not swim. Instead he set out to catch one. He used the remnants of the next bird he caught as bait. The first shark to pick up the taste was only a few feet long. He gulped the bait and hit the line with full force, but in preparation Poon Lim had braided the line so it would have double thickness. He also had wrapped his hands in canvas to enable him to make the catch. The shark attacked him after he brought it aboard the raft, so he used the water jug half-filled with seawater as a weapon. After subduing the shark, Poon Lim cut it open and sucked the blood from its liver. Since it hadn't rained, he was out of water and this quenched his thirst. He sliced the fins and let them dry in the sun - a Hainan delicacy.
On two occasions other vessels passed nearby: first an unidentified freighter, then a squad of United States Navy patrol planes. Poon contended that the freighter saw him but did not pick him up because he was Chinese. The Navy planes did see him, and one dropped a marker buoy in the water. Unfortunately for Poon, a large storm hit the area at the same time and he was lost again. He was also once spotted by a German U-boat, which had been doing gunnery drills by targeting seagulls.
At first, he counted the days by tying knots in a rope, but later decided that there was no point in counting the days and simply began counting full moons.