One of the missions in Assassin's Creed Odyssey: Judgment of Atlantis is called Fire Amid the Water. This page contains the full walkthrough for that mission.
What is the goal of this mission?
This mission is to create three weapons in the Forge of Atlantis. This location is in the southern part of the Royal Mountain of Poseidon.
To create a weapon, you need to get the project first. These are hidden in the archives.
Get the resources and then head to the Forge and get the selected weapon.
What weapons can I get?
You can forge a dagger, a mace and a spear. Their properties are up to you. You can choose a warrior, assassin and hunter weapon. Depending on how you developed your character, select the appropriate option, and the game will choose the improvements.
How to get raw adamant?
Raw adamant can be found in chests hidden in the archives. You need three of them to craft a weapon.