Puffing Tom

The Puffing Tom is Tom's only fully functioning Sea Train. Puffing Tom was built during Tom's original ten year hiatus from government persecution, with significant improvements added over the Rocket Man.

Design
Puffing Tom's design is based on historical 19th century American steam locomotives. It is a custom built 4-4-0 locomotive with a streamlined boiler and smoke box and an inverted cowcatcher. It has the words "Water 7" painted on its tender and runs on top of the water with a track to guide it. The color scheme was green and red with orange and yellow lining. In addition to its tender, Puffing Tom carries several passenger cars. During its trip to Enies Lobby several of these were destroyed by both the Straw Hat Pirates and the Franky Family. The Puffing Tom also has freight cars, only one of which was shown briefly, a flatbed car, bringing lumber to Water 7.

Creator's Pardon and Penalty
It was built by a fishman named Tom and his shipbuilding company, "Tom's Workers", Franky and Iceburg being among them. Tom built a ship, the Oro Jackson, for the Pirate King Gol D. Roger while Roger visited Water 7 and was found out by the government. The government wanted to sentence Tom to death, but when he presented his idea to build the Sea Train to pull Water 7 out of its depression, the government allotted the time needed, ten years, for Tom and his workers to build it. There were a few failures from prototypes like Rocketman due to its unstable (and unstoppable) speed. The Sea Train now connects over four islands and allows for travel and trade between them.

After Tom finally completed the Sea Train, Tom was finally allowed to be pardoned for any crime he desired. However, Spandam was angry at the hassles of trying to get Tom to hand over Pluton to him. Therefore, in an effort to secure the blueprints, Spandam hired people to steal and man the Battle Frankies that Cutty Flam (Franky) built, and attack Water 7 at the resumption of Tom's trial.

Though he knew Franky to be innocent, Tom took responsibility for the actions of his pupil's ships and decided to claim his pardon against the attack on Water 7. This action thus reinstated his original sentence and he once again was accused of building Roger's ship. Having overheard Franky disown his creations, Tom finally owned up to building the Oro Jackson; not only that, but claimed he was proud to have done so in order to show Franky the true meaning of being a shipwright. Tom was escorted on the sea train he built to Enies Lobby, and he is believed to have been executed shortly thereafter.

Enies Lobby
After events in Water 7, Sanji discovered Robin was onboard the Puffing Tom. Sanji stowed away after leaving a note/love letter to Nami about his plan. After the train was a short distance from Water 7, Sanji entered the Puffing Tom from his hiding place on the last car.

He quickly subdued the soldiers in the rear car including Jerry of CP6. In the following car he freed Usopp and Franky. After luring T-Bone and his men into the two rear cars he cut them loose.

Moving along with Franky and the disguised Usopp they encounter CP7's Wanze. Leaving Sanji to deal with Wanze, Usopp and Franky split up. While Usopp used his octoshoes to reach Robin, Franky became involved in a fight with Nero. All three people accomplish their task simultaneously and end up in CP9's car.

A desperate escape ensues with the three of them and Robin in the three rear cars. However, Blueno's Devil Fruit powers and Robin's unwillingness to be saved thwarted the escape and led to Robin and Franky's recapture. The Puffing Tom and its remaining cars continued to Enies Lobby.

Escape from Enies Lobby
As the Buster Call razed the government stronghold, the Franky Family, Galley-La Company foremen, and Oimo and Kashi commandeered the Puffing Tom and escaped back to Water 7.

Trivia

 * The Puffing Tom's name is based on the oldest locomotive in existence, Puffing Billy, as stated by Oda in SBS Volume 39.