Kerans observes the party going on on Strangeman's ship from an office building. Riggs is still at the party. He and Strangeman came to an agreement earlier that day and Riggs is successfully masking his distaste for Strangeman. Kerans watches Riggs and Beatrice leave the party and climb the testing station, which is serving as the landing pad for the helicopter. Sergeant Daley starts the engine. Kerans had put in a brief appearance at the party and tried his best to avoid Strangeman, but claimed he was feeling sick with malaria and left as soon as he could.
It's worth noting that the politeness that Riggs and Strangeman are showing each other is because they recognize that they share a common goal. Riggs wants to use Strangeman to help him drain the cities of Europe so they can be re-civilized in the future. Kerans can barely stand to stay at the party because he sees that the future that these men believe in is contrary to the future that nature intends for the earth.
Kerans runs along a silt bank at the edge of the empty lagoon. He's near one of the original inlets to the lagoon, which is blocked by heavy logs. Kerans pulls out two bombs, pilfered from Bodkin's stolen stash. He lights them, hangs them on the logs, and is interrupted by Sergeant Macready yelling at him from the top of a nearby building. Macready notices the bomb, begins shooting at Kerans, and runs towards the dam. Kerans yells at Macready to go back as one of Macready’s bullets hits Kerans in his lower leg. Macready stops right above the bombs as Kerans ducks for cover.
When Kerans uses bombs, something man-made, to ensure that the water can return to the lagoon, it's a final testament that man-made things aren't all bad. They can help bring about the future that Kerans knows is inevitable. Once Kerans violates civilized codes of conduct, other people turn on him and he suddenly becomes an enemy, just as the natural world has been an enemy to Riggs throughout the book.
When the bombs go off, silt and water fly into the air, and water flows into the lagoon. Strangeman's party begins to panic as the water reaches the depot ship, and then the entire silt dam disintegrates and rushes into the lagoon with immense force. Kerans hears Riggs call his name and turns as a shot whizzes over his head. Riggs is running toward Kerans from the helicopter pad. Kerans fires his gun at Riggs. None of his shots hit Riggs, but Riggs stops chasing Kerans.
Strangeman is punished here for hubristically believing that he was the most powerful individual in London, and for believing that he alone had the power to control the natural world. Kerans insists that the city return to its drowned state so it can continue to experience its rebirth and move forward into the drowned future.
Beatrice suddenly rushes for Kerans. When she reaches him, she implores him to leave and escape Riggs. Kerans tells Beatrice to tell Riggs he’s sorry for killing Macready. He looks out over the flooding lagoon and notices the depot ship floating upside down, though he can't see Strangeman or any of the crew. Beatrice asks Kerans where he's going and apologizes for not going with him, and Kerans explains that he's going south, "towards the sun." They embrace and then Kerans runs into the jungle. Daley and Riggs pursue him and shoot into the foliage, but Kerans evades their shots.
Despite his near total descent into a primal mindset that makes him detached from the world of men, Kerans still cares about Beatrice, and he's still entrenched enough in civilization to feel remorse for Macready. This shows that his journey has truly just begun, and that he'll experience far more dramatic changes as he heads south towards the sun and his eventual death.
Kerans locates his makeshift catamaran and pushes off into the next lagoon as Riggs continues to shoot at him. When Kerans is able to steer the catamaran behind some buildings, he looks back and sees Beatrice waving from the top of a building. Kerans takes a final look at the Ritz and can even read Strangeman's joke, "TIME ZONE," written on a building. Kerans hides in a building while the helicopter circles overhead, and when it leaves, he navigates to the inland sea that will take him south. He sets his sails, attends to his leg, doses himself with morphine, and falls asleep.
Now, the written "TIME ZONE" indicates that Kerans will truly enter a different zone of time as he heads south. Human systems of timekeeping don’t apply anymore as he continues to descend into the neuronic past. His pack of medical supplies shows that he's still mindful of the need for supplies to help him survive on this journey, which shows that he hasn't yet made the final leap to rejecting all man-made objects in favor of the natural world.
When Kerans wakes, he notices that the helicopter is flying a mile away, shooting into the islands. Kerans hides. The helicopter patrols and shoots every half hour for most of the day. By late afternoon, Kerans is exhausted in the 150-degree heat. He lies on his back and hallucinates that the water is fire.
At this point, the heat is still affecting Kerans as though he's not one of the dreamers. The fiery world of his hallucination shows that on some level, he is aware that the heat will ultimately be what kills him.