It's in letter 4.
Answers 2Add Yours
Wouldn't that be the ship that Walton is on?
Walton frames the story by being the one outsider who encounters Frankenstein and knows the whole story. He is the audience for Victor, the man who has the same ambitions as Victor but reconsiders them after hearing the whole horrid tale and even meeting the creature. He is about to kill himself and his crew in his quest for immortality. Victor's story convinces him to "seek happiness in tranquility and avoid ambition."