Answer:
After Mr. Cao told him that people often drowned in Heaven Lake, the author got scared and decided against getting into the lake, so he retied his shoes.
Step-by-step explanation:
In the book From Heaven Lake: Travels Through Sinkiang and Tibet, Vikram Seth describes his trip around China, and in the chapter titled Heaven Lake, he describes his visit along with his friend John to Heaven Lake. There, Seth wants to go swimming, so he unties his shoelaces. However, after Mr. Cao´s warning, Seth decides against it, and, therefore, he reties his shoelaces.