Assassin's Creed Odyssey

To unlock this achievement you need to destroy an enemy ship by cleaving it in half. To achieve this you have to ram into the side of the ship with a killing blow. You can damage the ship however you like but the final blow has to be a ram into it's side. You can get this on the very first ship you fight against when you first gain control of the Adrestia, head to the objective and there is a ship you need to destroy. If you can get a ram into the side of it before it moves off you can reduce it's health to around half. It will then try to manoeuvre away but you can just wait until it stops again to then line up another shot at ramming it's side. It took me three hits on the easiest difficulty to destroy it.

You can use to speed the ship up temporarily and doing this gives you a more powerful attack when ramming, however this is controlled by a meter that runs out rather quickly (although recharges itself almost immediately), so be sure you have enough to get a good speed charge into the enemy ship. Once the enemy ship is destroyed in this way, the achievement will unlock.