An entire sector of saltwater pools, all of which seem to be filled with dangerous creatures. But so far no signs of how to get into the Phylactery Vault.
In need of a long rest, but knowing it is not safe to do so within the Doomvault, you make your way to the nearest Black Gate. Unfortunately, it is guarded by several Scrags (aquatic trolls).
After dealing with the Scrags, and having a conversation with Nabu, the adolescent Dragon Turtle befriended by Brehana you make your way back to the Gate House using the Black Gate.
There you discover that the lake Nabu wishes to return to is just a few hundred yards to the west of the Gate House so you return to the Doomvault to retrieve Nabu. After some emotional goodbyes and promises to rescue him from Thay so he can live with you all near Xonthal’s Tower, Nabu is taken to Lake Thaylambar.
After taking a long rest, you return to the Doomvault and push deeper into the sector known as the Predator Pools where you discover a pool full of floating undead and who knows what other abominations.