River Euonë
Planar pathway
The River of Remembrance, Euonë runs alongside the Lethe from their joint source in Chronias as far as Lunia. There Lethe goes underground and Euonë joins the ocean. Euonë appears similar to Lethe, but has a miraculously different property. Whoever drinks the water of the River of Remembrance regains memories lost by magic or psionics or by drinking the waters of the Styx or Lethe. However, traumatic experiences are rendered less awful by the process, and so many use it as a means of spiritual refreshment. Of course, to partake of it you must first be able to travel around the Holy Mountain, which prevents evil or overly chaotic berks from using it. [The effects resemble those of the spell blessed remembrance.]
Source: Alex Roberts. This planar pathway is a homebrew addition to the lore.