Kanai watches Piya walk away, hoping she'll visit—he's unmarried but has had a long string of sexual relationships with women, the most recent of which ended badly. He hopes Piya will be a grand distraction. When he steps off the train, he remembers being here 30 years ago, and how he had been astonished at how many people lived in Canning.
Kanai’s astonishment at the population in his youth shows that his sense of superiority started early in life, as it implies that he didn't think Canning was important enough to have a larger population.
Kanai also thinks about the last time he saw Nirmal in Calcutta in the late 1970s. Nirmal had been perusing books when Kanai barreled into him on his way to class. Kanai bought Nirmal the book he'd been looking at, and he always thought he'd run into Nirmal again like that. However, Nirmal died two years later after a long illness. He'd mentioned some writings that he wanted Kanai to have, but nobody could find them. Suddenly, two months ago, Nilima had found them and called Kanai, asking him to visit. Kanai had tried to put her off, but finally agreed to come.
This backstory sets Kanai's journey up as being one in which he comes to terms with his past and possibly the way he moves through the world. His unwillingness to come deal with Nirmal's writings again implies Kanai's own sense of superiority, which suggests that he'll have to challenge that sense by returning to Lusibari.
Back on the platform, Kanai spots Nilima sitting, surrounded by admirers and well-wishers. When she spots Kanai, she snaps her fingers, which causes the crowd to disperse, and greets Kanai. As she leads him out of the station, Kanai tells her about meeting Piya on the train and says he invited her to visit. Nilima asks if Kanai read the papers she sent—the papers Kanai read on the train—and Kanai is disappointed that they're not from Nirmal's packet. Nilima asks why Kanai insisted on coming through Canning, and explains that the river has changed.
Nilima's mention that the river has changed shows early on that what Nirmal wrote in the papers Kanai read on the train is absolutely true: the Sundarbans are a place where nature has the power to shape the world to its liking, with little or no concern for the humans who may rely on certain waterways. This situates the natural world as one that's indifferent to its inhabitants.
When Kanai and Nilima reach the river, Kanai sees what she meant—at low tide, the half-mile wide riverbed is mostly mud with a ditch running through the middle. He watches in disbelief as passengers jump off a boat in the middle and wade through the hip-deep mud to shore. Kanai apologizes for insisting on coming through Canning and explains he just wanted to revisit where he arrived in 1970.
Because the river is part of a delta, the ocean's tides impact it. These tides are influential in how people in the Sundarbans live their lives, reinforcing the power the natural world has over people in this part of the world. In this case, the passengers simply have to deal with what the natural world has dealt them by wading through the mud.
Kanai starts to reminisce about Nirmal, but Nilima stops him. She explains that they "found" him in Canning, and he died months later. It was around the time of the Morichjhãpi incident, which she explains was a violent confrontation between police and refugees who had settled on an island. They bused the refugees away, and she believes that Nirmal was let off of one of those buses. Nirmal had been so disoriented, he could never tell them what happened. He'd simply yelled that the Matla would rise.
Nilima's apparent discomfort with talking about the last months of Nirmal's life suggests that she hasn’t fully recovered from whatever happened. This suggests either that she simply doesn't have the language to adequately describe what happened, or that what happened was very out of character for Nirmal and was therefore beyond comprehension.
Kanai says that that was surely a reference to Nirmal's favorite story about Henry Piddington and the port of Canning, but Nilima cuts him off; she insists it's too hard for her to talk about Nirmal. Kanai goes silent and remembers the first time he was in Canning. He and Nilima had waited while Nirmal, a copy of Rainer Maria Rilke's Duino Elegies clutched to his chest, unsuccessfully watched for a boat. A local named Horen had rescued them. Horen told Nilima that Bon Bibi, the forest goddess, had granted him honey. Kanai had laughed that people believe in such nonsense, but stopped quickly when Nilima suggested Horen could teach Kanai a lesson.
When Nilima reprimanded Kanai when he was young, it shows that she's adjusted to life in the tide country and understands that the local religion and local beliefs must be respected. This is one way that Nilima adjusts to the specific language of the tide country—she essentially insists that Kanai must do the same if he expects to have a reasonable time on Lusibari.
Horen had offered to take them all back to Lusibari, and Nilima accepted. She explained to Kanai that Horen was a fisherman with three children, though he wasn't yet twenty. He was also caring for Kusum, a teenage girl. Kanai didn't understand Nilima's euphemisms as she explained that Kusum may have been forced into prostitution without Horen's help, but Kanai was intrigued regardless.
Kanai's interest in Kusum suggests that his interest in women as objects of fancy started early, given that she's the only thing that has thus far piqued his interest since arriving in Canning. Horen's life story suggests that life in tide country is very difficult, given his young marriage.