Some critics find it hard to believe that Jonah could survive inside a large fish. They challenge one of the book's main ideas, that God has complete control over nature. If God exists and created nature (Jonah 1:9, 16; see also Genesis 1:21), such a miracle is possible. The book treats the fish story as historical.
The species of the fish is not specified, nor is it important for the story's meaning. Given God's power, the fish could have been specially created for this event. If God can perform miracles, Jonah's need for air and protection from digestion is not a problem (see Daniel 3:14–27). Some fish, like the whale shark, are large enough for this purpose, and similar events have happened in modern times.
Jesus later mentioned Jonah's three days and nights in the fish to predict his own time in the grave (Matthew 12:39–41).
The phrase appointed appears four times in the book, showing God's easy control over nature (Jonah 4:6, 7, 8).