* Eel migration: Eels are known for their long migrations, but their destinations are usually related to breeding and life cycle stages. For example, some eels migrate from freshwater rivers to the ocean to spawn.
* Tonga's location: Tonga is a nation of islands in the South Pacific. While eels can be found in the Pacific Ocean, Tonga isn't a known destination for any specific eel species migration.
* Lack of evidence: There isn't any scientific evidence or anecdotal information suggesting eels migrate to Tonga in large numbers.
Therefore, the statement "eels swim to Tonga" is likely a misunderstanding or a fictional concept.