One day the lifeboat drifts into a mass of floating trash. Pi picks out a corked, empty wine bottle. There is a refrigerator, but all the food inside is horribly rotten. Pi writes a message about his predicament, seals it in the bottle, and throws it back into the water.
This is another attempt at communication with the outside world, although a pretty hopeless one. Pi does get a sign from humanity, but it is only trash and waste.