the word "boiling" in "the crowd is boiling again" means: it is a metaphor for high emotions and noise. From Watching the Tide, this paper describes the grand occasion of watching the tide, describing the scenes before the tide comes, when the tide comes and after the tide head, describing the whole process of the tide from far to near and rushing to the west, depicting the dynamic changes of the river tide from calm to roaring and then restoring calm, and writing out the strangeness, grandeur and grandeur of the tide.

Excerpt from the original text:

At about one o'clock in the afternoon, there was a rumbling sound from a distance, like a muffled thunder rolling. Suddenly, people were buzzing, and someone told us that the tide was coming! We stood on tiptoe and looked east, but the river was still calm and there was no change. After a while, the noise became louder and louder. I saw a white line in the east where the water and the sky met, and the crowd boiled again.

Appreciation:

In Watching the Tide, the author not only directly describes the situation and prestige of the surging tide by means of metaphor, description and foil, but also indirectly shows the strangeness of the tide from the number of people watching the tide and the high enthusiasm. In this way, the direct description and indirect contrast will vividly show the wonders of Qiantang autumn tide in front of readers.