After swimming for a few tens of miles, the group arrives at the Mermaid Fortress in that area. The place is a set of stone buildings that float inside the water by magic, similar to the other fortress that Lucien saw on the border of the Naga territory.
But unlike that fortress, where Lucien saw thousands of Nagas swimming around, there isn't a living soul within miles around, which creates a very strange atmosphere.
The Sins expand their magic sense through the area and discover various things like magic devices, weapons, high mana foods, and even the portal that Nea mentioned, but there is no person or creature around.
The group heads towards what appears to be the main building, then Lust feels something strange and exclaims in Lucien's mind. 'Dark mana!!'
'Another shark???' He quickly asks as he goes into a state of alert, drawing Nea and Saria's attention.