This page offers a guide on where to locate and how to complete Seahenge, which is a Mystery located in East Anglia.
Align the Symbol
This mystery is found north of Elmenham. First off, you’ll need to interact with the black symbol on the rock to begin the mystery. Then, use Odin’s Sight to reveal the hidden symbol on the tree and the stones surrounding. You’ll want to stand facing east, looking directly at the tree from the edge of the pool of water near the reeds. Then, adjust your positioning until the symbol begins to glow and the camera zooms in, and then you’ll have completed the mystery and you’ll earn +1 Skill Point.