The novel is about a prospector named Josiah Flintabbaty Flonatin who explores a bottomless lake in a submarine, and discovers a land where the norms of society are backwards.

The story centres on the lead character, a prospector named Professor Josiah Flintabbaty Flonatin.

Flonatin, who is a bachelor, decides to escape the city, and does so by climbing out of a crater, which is actually an extinct volcano.

[2][3] The Sunless City had been read by Thomas Creighton, a prospector who had been exploring in the area of what would become the town of Flin Flon.

In one account an associate of Creighton had brought some gold out of a hole from one of their claims, according to this account Creighton said:[4] That must be the hole where old Flin Flon came up and shook his whiskers, so what do you say we call the discovery Flin Flon?A second account of the naming of the discovery suggests that the back pages of the book were missing (stopping at the point in the novel where Flonatin is climbing out of the crater), following Creighton's reading of the book, he approaches a deep hole, approximately 10 feet (3.0 m) wide, and said to his associates:[3] Boys, I guess we've found old Flin Flon's mine.In 1962 a statue designed by Al Capp of Josiah Flintabbatey Flonatin was built in Flin Flon.