Ahtohallan is an ancient river that appears in Disney's 2019 animated feature film Frozen II. Described as a river "full of memory", Ahtohallan holds all the answers to the past. The river is a prominent part of the Northuldran culture, who sing about Ahtohallan in their lullaby "All Is Found". Though widely believed to be a mere myth, Ahtohallan is real and takes the form of a glacier (which, in layman's terms, is a river of ice).
Located on the Dark Sea. Ahtohallan acts as something of a visual archive. By projecting scenes from history along its icy walls, Ahtohallan allows its visitors to learn all there is to know about their past, and the people connected to them. However, traversing Ahtohallan's caverns can be extremely treacherous. As "All Is Found" warns, those who go too deep into Ahtohallan will "drown" (in reality, turn to ice).
- According to Iduna's notes, Ahtohallan is the source of the magic in the Enchanted Forest as well as those of the spirits, including Elsa’s powers.
- It can be assumed that Ahtohallan has a form of sentience as it called Elsa to it so that she could become the fifth spirit and discover the truth about the past. And when she views the memory of her mother in Ahtohallan and realizes that she is the fifth spirit, she says "I am found" as it says "you are found", personally addressing Elsa.
- It can also be assumed that it is the "magic of nature" to which Yelana referred as it gave Elsa her powers.
- Ahtohallan has a special connection with the spirits of the Enchanted Forest. While Elsa, the Nokk, and Bruni were able to hear Ahtohallan's calls, others like Anna and Kristoff were not.
- Ahtohallan may be a name created from the Finnish language or one of the Saami languages: "Ahto" (the Finnish god of waters) and "halla" (frost on the ground).