Path of The Crashing Tide

He was a flurry of blows, each more crushing than the last. As his axe struck down upon my shield it felt like the weight of a thousand depths had been dumped upon my body... in an instant I was on my back, and he was upon me. With fury in his eyes, and an insatiable desire to see me dead, he had forgotten this was a sparring match...

Tidal Surge

Beginning at level 3, while raging, whenever you hit a creature with a melee weapon attack, you may immediately use your bonus action to force the creature to make a Strength save or be knocked prone. Your save DC is equal to 8 + your proficiency bonus + your strength modifier. On a successful save, the creature is not knocked prone.

Up onto the overturned keel...

Starting at 6th level you are immune to being knocked prone while raging.

Additionally you may ignore non-magical difficult terrain in and out of combat.

Abyssal Assault

Beginning at 10th level, whenever you hit a creature with tidal surge, you may force another creature within 5 feet of your primary target to make the same strength save or be knocked prone.

Soothing Waters

Starting at 14th level, you gain an additional pool of d12 hit dice called "Soothing Waters Dice", the number of dice is equal to twice your barbarian level rounded down.

Soothing Waters:

Whenever you take damage from a creature that is within 5 feet of you, you may use your reaction to call upon the primordial water spirits immediately expending a number of soothing waters dice and regaining hit points equal to the value rolled. Any expended dice are regained at the end of a long rest.