Belly Flop

M was a virtual representation of one of Kassandra's genetic memories, relived by Layla Hassan through the portable Animus HR-8.5.

Riddle
''At Scavenger's Coast, north of Pellene, young people gather to dive through a hole in the cliff. Find me at the bottom... if you dare to take the leap!''

Outcome
Kassandra found and recovered the treasure.

Reference

 * Assassin's Creed: Odyssey