There is lone "werewolf " on Siptah, L9 - Grove of Jorgan.
He can drop Midnight potion or recipes for it, or there can be altar of Jhebbal Sag where potin can be crafted.
Since Midnight Grove is a spiritual place it easily can be accessible from Siptah
Sunken City is different story, but there could be some underwater interesting placer, given the massive amount of accessible water (That Skull on the north was so interesting and so dissapointing)