Barbarians upon the Path of Crashing Waves do not merely revere the ocean; their bodies physically manifest the crushing weight, relentless kinetic energy, and freezing depths of the primordial waters when their rage takes hold.
In combat, they move with the fluidity of a crashing tsunami, dragging enemies into their undertow and shattering the frontline with freezing pressure.
Your body adapts to the primordial waters. You gain a Swim Speed equal to your Speed, and you can breathe underwater.
You gain Darkvision out to 30 feet. If you already have Darkvision, its range increases by 30 feet.
Additionally, you have an intuitive ability to speak, read, and write Primordial (Aquan).
When you enter your Rage, your metabolism and sense of balance change. You gain the following benefits while Raging:
Durability of the Depths. You gain Resistance to Cold damage, and you ignore the effects of underwater pressure.
Flowing Movement. You can move through the space of any hostile creature, though you cannot willingly end your move there. Opportunity Attacks against you are made with Disadvantage.
Riptide. You can make an Unarmed Strike against a creature as a Bonus Action, but only to Grapple or Shove.
Undertow. When you successfully Grapple a creature, its weight does not halve your Speed.
You can move across the surface of any liquid (including water, acid, mud, or snow) as if it were harmless solid ground. You take no damage from walking across hazardous liquids in this way, though being submerged in them affects you normally.
If you are at least partially submerged in water or are drinking water, as a Magic Action you can expend one of your Hit Dice to roll it and regain Hit Points equal to the roll plus your Constitution modifier. When you use this feature, you can also end one of the following conditions on yourself: Blinded, Deafened, or Poisoned.
Before rolling the damage for your Brutal Strike, you may choose to have the extra damage be Cold damage. Additionally, when a creature takes Cold damage from your Brutal Strike, you have the following additional effect option:
Numbing Strike. During the creature's next turn it can take either an action or a Bonus Action, not both, and cannot gain the benefits of the Dash action.
You have Resistance to Bludgeoning and Cold damage, and ignore the effects of underwater pressure all the time now, not just while Raging.
Elemental Affinity. You gain the creature type of Elemental (Water) in addition to your other creature types, and you suffer no ill effects from the environment of the Elemental Plane of Water. The initial disposition of Water Elementals towards you is one category better than it normally would be, and they will not attack you unless their disposition changes to hostile. However, the initial disposition of Fire Elementals towards you is one category worse than it normally would be.
Eyes of the Deep. The range of your Darkvision increases by an additional 60 feet.