In World of Warcraft, the Fathom Dweller is back – a unique mount that makes you faster in underwater areas. The bizarre jellyfish is actually quite easy to obtain, but it was missing for months. Now it is back for a few days.
What kind of mount is this? The Fathom Dweller is a jellyfish-like creature that you can only use when you are in the water. It increases your swimming speed, making you faster in the water, something that only a few mounts or abilities can do.
Actually, the Dweller is easy to get, but it wasn’t showing up for months. It is one of two rewards from a weekly quest that appears randomly. For a long time, however, only the alternative reward, a pet, appeared week after week.
Now the quest is active again and you can get the Fathom Dweller.
How to get the Fathom Dweller
Where do I get the mount? You will find the Fathom Dweller as a reward for the world quest “DANGER: Kosumoth the Hungerer” from the old expansion Legion. For this, you just need to kill a boss, which you can even do solo at level 60.
The quest is located in the “Eye of Azshara” area – in the overworld, not in the dungeon. Just swim or fly to the small island directly south of Dalaran in the Broken Isles (Legion).
Here you can find the island. 
The world quest with the reward.
How to unlock the quest: To access Kosumoth, you first need to unlock the world quests in Legion. You must complete the quest “Unification of the Isles,” for which you need friendly reputation with all factions of Legion.
You can get the quest starting at level 45 and only need to complete it on one character. All subsequent characters (“twinks”) will then automatically meet the requirements.
After that, however, you still need to find a few things scattered in the areas of Legion. In our guide, we described how to get the Fathom Dweller in WoW and what you need to do for it. Plan about an hour for this task.
Reasons to hurry: If you are still missing the mount, you should hurry, as the quest is only available until Tuesday, January 12. It will reappear after that, but we cannot say whether it will offer the mount as a reward again. Many players have been waiting a long time for this opportunity.
Tip: If the mount does not show up as a reward, you probably already have it. Anyone who already possesses the Fathom Dweller will instead receive the alternative reward: the pet “Hungerer Claw.”
