To summarize from the last post, the Surfer was stripped of his heraldic duty and imprisoned on Earth by Galactus:
Although outwardly it is a punishment for foiling the desires of Galactus to consume Earth, I believe the barrier was created to stop the Surfer from returning to Zenn-La, which will be expounded later in the story.
According to a synopsis by Wikipedia, The Belly of the Whale is defined as a representation of the final separation between the hero’s known world, and the self. In this case, it is literal as well as figurative. Although I connected Norrin Radd’s sacrifices upon the Inner Crossing of the Threshhold to the Ordeal, this Belly of the Whale connects to an outer Ordeal, or Road of Trials. While the previous difficulties are revealed Unknowns (and serve as Temptations & Challenges later), this is very much within the Known World again.
In fact, for many years, Stan Lee used the Surfer to make commentary on social issues of the late ’60s. For the time that the Surfer was bound to Earth, he would give the outsider’s view of humanity on earth, while reflecting on his own.