South Mareotis Trireme
One of the mobile forts on Lake Mareotis. This has only a single goal- kill the captain. Find him by scanning with Senu, but remember that, like all triremes, part of the security here will be on small boats running alongside, not the trireme itself. Ignoring these outrunners is just asking for an arrow in the back.
Still, this is one of the lowest level forts in the game- while you could easily snipe him from a distance, there's really nothing stopping you from just hopping aboard and slaughtering you way to the captain. Either way, killing him completes the location.