On this page of our Assassin's Creed Odyssey solution you will find guidelines about Ainigmata Ostraka (Ostracons) puzzles in the Abantis Islands location. Here you will find info about the following riddles: Everything for Freedom and Beneath Theseus's Dreams.
Everything for Freedom
Location of Ainigmata Ostraka: Oreos Quarry, Eubuea.
How to solve: Check the picture above - you have to get to the figure with a bull on the top of the hill.
Beneath Theseus's Dreams
Location of Ainigmata Ostraka: Skiros, Pirate Hideout, not that far from the sea.
How to solve: Get to the Hero's Fall and jump down. Dive into the water and swim to a shipwreck. There you will find what you're looking for.