The Ancestral Reef is a small, unmarked-on-the-map landmark in the Manoa Lai sea in Endless Ocean.
This tiny pocket in the surrounding rock structure is home to a flock of Brown Boobies, diving for food, a shoal of Japanese Jack Mackerel, and several smaller kinds of fish, including Moorish Idols, Green Chromis, Yellow Tang and Longnose Butterflyfish. The easiest way for the player to know if they've found this location (aside from the on-screen text box) is to look for the diving birds, which only appear here and on the player's boat, the Gabbiano.
Location and Geography
the Ancestral Reef can be found just West of the Mermaid's Grotto, at coordinates K-7 in the Southeastern area of the Manoa Lai Sea.
Within the Reef itself, on the sandy seafloor, the player can find one of the pieces of the Storyboard
treasure resting under a zoom-mode glow.