- “Engines don't swim, Henry - you were meant to deliver fish, not swim with them. You should know that by now.”
- ―Sir Topham Hatt scolding Henry
Thomas is at the quayside and is about to take vans full of fish to Brendam Docks for Henry's train, The Flying Kipper. The start of his trip to Brendam is delayed by a crate of fish accidentally falling onto him.
Next, as he travels along the Coastal Run, he is furthered delayed by a man who informs him and his crew about some tracks eroded from high tides. While the tracks were safe enough for Thomas, they could not bare the weight of a heavy engine like Henry. The guard places a red lamp pole by the damaged track as a warning spot, and once Thomas arrives at Brendam Docks, Henry does not listen to Thomas' warnings and leaves before the signalman can be warned. In a rush, Henry cannot see where he is going due to the fog, and once he does, he puffs straight into the sea and has to stay there all night until he is rescued. When Henry is temporarily put in a barge full of fish, the Fat Controller scolds him, saying that engines do not swim.
After Henry is back on the rails, Thomas comes to take him away for a washdown and Henry apologises for being rude to him. Thomas then jokes with Henry about the whole adventure.
- Sir Topham Hatt
- The Lighthouse Keeper (not named)
- James (cameo)
- Big Mickey (cameo)
- The inspiration partly for this episode may have come from the magazine story, A Fishy Smell.
- This episode marks the last appearance of The Flying Kipper until the sixteenth season episode Whiff's Wish, excluding two stock footage appearances in the seventh season.
- In the UK version when Thomas says "I can't help it, it's the fish!" the steam appears forward, then is played backwards, then played forwards again, meaning that the film was cut, but edited.
- After Henry reaches the fog, he loses two vans.
- Before Henry falls into the sea, his brakes are applied and his wheels stop moving, but when he runs into the sea, his wheels are moving again, despite the braking sound effects still being audible.
- When Thomas puffs away with Henry at the end of the episode, the puffing noise starts long before Thomas moves.
- In the US version, when Henry says "I can't see!" the first horn "honk" is barely audible.