Recently I took Garrrin (Level 22 Barbarian/Fury of the Wild) through the quest, Into the Deep. Into the Deep is the capstone quest for the Red Fens. To access the quest, you have to complete the other three quests out in the Red Fens: The Last Stand, Fathom the Depths, and The Claw of Vulkoor. The order in which you complete these three is open.
The quest Into the Deep is unique in a few aspects. First off, it actually takes place at the bottom of the inlet that leads into the Red Fens on the seafloor. So the quest actually occurs underwater. Now there are plenty of quests where you have to swim through to get to one side or another, but this particular quest is entirely underwater. Now, with that said there are three temples that you have to navigate to and once you enter those temples, the water is sealed out so it is like you are traveling above ground normally. But, navigating the tunnels requires you to travel along the seafloor and completely under water. To do this, a rebel sahaugin casts a indestructible air bubble around you that you can use to breathe, move, attack, and swim with. You can encounter a number of sahaugin guards as you are moving along seafloor who will attack from above as well as from the seafloor.
The first thing you need to do with this quest, is to head into the east and west temples and free the imprisoned water elementals. Once these elementals have been freed, then you will be able to access the main temple in the north of the map. The water elementals have been frozen and you have to break them free from their frozen prisons. In the west temple, you have an optional to free the drow slaves and in the opposite temple you have an optional to destroy the scrag miners. In the west temple, there are also two secret doors, one of which hides a chest. The enemies in the temples consist primarily of high priests, elite warriors, high mages, and other sahaugin badies. You will also encounter corrupted water elementals and scrags as well. The mages and clerics can be easily difficult to deal with in large numbers. In the west temple, when you are working on destroying the frozen prison of the water elemental you will be attacked by wave after wave of sahaugin and corrupted water elementals until the frozen prison is free. In the eastern temple you have to make your way past respawning scrags and sahaugin as well as destroying a huge scrag mutant to get to the higher level to take on the high priest and free its water elemental.
Once these two elementals are defeated, you can move to the northern temple. In their, you find that the rebellious sahaugin, the ones that helped you as you started the quest, have taken back control of the front portion of the palace and are not ready to help deal with the high priest. You basically get a hoard of sahuagin warriors to help you deal with wave and wave of enemies. After a few waves, you will be able to make your way up to the higher level where the High Priest is taunting you and to defeat her. At that point you have completed the quest.
Now, there is one more optional you could do. You can leave out of the northern temple and head south to the main platform area and swim down. This was blocked and sealed, which breaks when you free the elementals. Down this deep shaft is a very dangerous Hezerou that repawns a score of fire reavers. This particular fight can be brutal. Howeer, on epic settings, this is the fight that needs to be completed to get your epic chest. This is perhaps the hardest fight in the entire quest.
Another optional objective is to collect a special sea plant that can the bee turned n for some small reward. On top of that, there is slaying optional in the swimming area where you can work on reducing the enemy forces.
Currently, this is the only quest you can fight underwater in. It is a fun quest, but it can be challenging if you are trying to solo it and you gather too much aggro. But it is a fun quest . If you ever get into the Red Fens I would recommend completing the flagging quests and running through the quest Into the Deep. Thanks for reading everybody and happy hunting!!