Nami serves as the navigator for the Straw Hat Pirates. Spotting an attacking Marine ship during an encounter with Marine Captain Trap, she identifies a Kung-Fu Dugong leaping toward the Thousand Sunny. She intervenes to stop Franky from attacking the dugong, clarifying that defeated Kung-Fu Dugongs become disciples of their victor.

Forced into Trap's elaborate tower structure alongside her crewmates, Nami endures the hazardous ride. She withstands the water tunnel segment even as seawater weakens the Devil Fruit users. Later, she praises Sanji after he disables the Hammer Hell trap.

When the ship enters a room filled with dugong-operated cannons, Nami employs her Thunderbolt Tempo technique in an effort to rouse the seawater-exposed, groggy Luffy. After Luffy deflects the cannonballs using his Gomu Gomu no Balloon ability, Nami instructs him to deal with the remaining threats.

Following their escape from the collapsing tower, Nami expresses frustration at Luffy agreeing to a dugong rematch. She physically admonishes him and commands Brook to use his sleep-inducing music on the creatures instead. Her actions throughout demonstrate her established role as the crew's navigator, showcasing observational skills, combat support via weather-based techniques, and authoritative decision-making during crises.