The Question and Answer section for Three Men in a Boat (To Say Nothing of the Dog) is a great resource to ask questions, find answers, and discuss the novel.
The narrator, J., is smoking in his room with his friends, George and William Samuel Harris, and his dog Montmorency.
What chapter are you referring to.
The men had uknowingly moored the boat near a swan's nest that was harboring young hatchlings. The mother wasn't very happy about it and attacked him, an act that was quickly followed by the attacks of even more swans.