Path of the Depths

Encounters with the terrors of the deep can break the minds of the weak-willed, but some forge their trauma into weapons never seen above the waves. The barbarian who walks this path has survived such an encounter and has gained extraordinary abilities from the experience.

Source: Legends of Runeterra - Dark Tides of Bilgewater 

Gift of the Drowned Ones

At 3rd level when you adopt this path, you gain a swimming speed equal to your walking speed and gain the ability to breathe underwater.

Dredge Line

Starting when you choose this path at 3rd level, you manifest an extra appendage when you enter your rage. This weapon can appear as a kraken tentacle, a giant anchor, preternatural jaws, or something else based on your history. As a bonus action, you can use lash out with this appendage to a range of 15 feet. If you strike a creature, make an attack roll which you add your Strength modifier and your proficiency bonus. On a hit, the target takes 1d6 Slashing, Piercing, or Bludgeoning damage plus your Strength modifier (your choice when you first gain this feature). When you reach the 6th level, your extra appendage is considered as magical for the purpose of overcoming resistance and immunity to nonmagical attacks and damage.

Additionally, if the creature you hit is your size or smaller you can force them to make Strength saving throw (DC equal to 8 + your proficiency bonus + your Strength modifier) or be pulled up to 10 feet in a straight line towards you. Alternatively, you can target a wall or sturdy object within range and pull yourself to within 5 feet of it, this movement does not provoke opportunity attacks.

Ghostwater Dive

Beginning at 6th level, you can burst into water then materialize somewhere else as an action. You magically teleport along with any equipment you are wearing or carrying, up to 30 feet to an unoccupied space you can see. Before or after teleporting, you can make one attack, as part of your action. Moving in this way does not provoke opportunity attacks

Manifestations of the Deep

At 10th level, you can manifest additional adaptations of the deep. Select one of the below adaptations you manifest, during a long rest you may replace your chosen manifestation with a new option from this list.

Armor of the Deep

Your skin hardens increasing your Armor Class by 1

Arms of the Deep

While raging, you now manifest two magical appendages, which may be tentacles, chains and anchors, animated rigging, or another grasping arm of your choice. When you use your dredge line ability, you can attempt a grapple with each of
your appendages.

Eyes of the Deep

You gain the ability to use echolocation. When you do so, you cast the true seeing spell, without using a spell slot or material components. After you cast a spell in this way, you can’t use this feature again until you finish a short or long rest

Heart of the Deep

You can use a bonus action to gain temporary hit points equal to 1d12 + your barbarian level. Once you use this feature, you must finish a short or long rest before you can use it again.

Soul of the Deep

You are now immune to all effects that would cause you to be charmed or frightened

Depth Charge

At 14th level, when you use your ghostwater dive ability, you can choose to appear with a wave of tidal force. When you appear all creatures within 10 feet of you must make a Strength saving throw. On a failed save a creature takes 3d6 force damage and is knocked prone. On a successful save, a creature takes half damage and is not knocked prone.