Mana’s son with crooked fingers,
Iron-pointed, copper fingers,
Pulls of nets, at least a thousand,
Through the river of Tuoni,
Sets them lengthwise,
sets them crosswise,
In the fatal, darksome river,
That the sleeping Wainamomen,
Friend and brother of the waters,
May not leave the isle of Mana.
Tuonen poika means Son or Boy of Tuoni (Death, ruler of Tuonela). Together with other inhabitants of Tuonela, the Son of Tuoni weaves an iron net and sets it across the River of Tuonela to prevent the wizard Väinämöinen from leaving Tuonela.
In the morning, Tuoni’s Son looks for Väinämöinen in his net. He does not find Väinämöinen who has transformed into a snake and swum through the nets back to the world of the living.
In Kalevala, Lönnrot has given the Son of Tuoni an additional role that cannot be found in ancient poems: he kills Lemminkäinen in the River of Tuonela with his sword while he is floating in the River of Tuonela.