Jonah was a Biblical figure who was swallowed by a large sea creature.
In 2371, when Neelix requested permission to leave the USS Voyager when the crew encountered a nucleogenic cloud being, Captain Janeway denied his request, stating "find yourself a seat with a good view, because just like Jonah and the whale, you're going in." (VOY: "The Cloud")
In a log entry made by Lieutenant John Kelly of the Earth spaceship Ares IV in 2032, the lost astronaut remarked that he was beginning to feel like Jonah; Kelly remarked that he had been trapped in the vessel longer than Jonah was in the "belly of that whale". Kelly's log was lost for centuries until it was discovered in the Delta Quadrant by Voyager in 2376. (VOY: "One Small Step")