Critical theologians take this entire story to be allegory—not history. Jonah represents the Jews, the great sea represents the Gentile nations, the great whale represents Babylon, and the Great Fish represents the Exile. After Jonah (Israel) spends several days in the Great Fish (the Exile), he has a different attitude toward God’s will in reaching the Ninevites (the Gentiles). However, there are a number of problems with this allegorical interpretation:
First, nothing in the text gives us an indication that it is allegorical. Instead, it presents itself as historical in its genre.
Second, other biblical authors interpret this work as historical—not allegorical. Jonah’s work is mentioned in 2 Kings 14:25 as historical work. Kings says, “He restored the border of Israel from the entrance of Hamath as far as the Sea of the Arabah, according to the word of the LORD, the God of Israel, which He spoke through His servant Jonah the son of Amittai, the prophet, who was of Gath-hepher” (2 Kings 14:25; Compare with Jonah 1:1 “son of Amittai”). Moreover, and most importantly, Jesus compared Jonah’s historicity with the historicity of his resurrection from the dead (Mt. 12:39-41), which is essential Christian doctrine (1 Cor. 15:12-19).
Third, the allegory breaks down. For one, why would the allegory give three days in the whale to symbolize seventy years in Exile?