Bite

Melee Weapon Attack: +5 to hit, reach 5 ft., one target. Hit: 8 (1d10 + 3) piercing damage plus 3 (1d6) cold damage.

Tidal Breath (Recharge 5-6)

The dragon exhales a crushing wave of frigid seawater in a 15-foot cone. Each creature in that area must make a DC 12 Dexterity saving throw. On a failure, the creature takes 11 (2d10) bludgeoning damage and 11 (2d10) cold damage and is pushed up to 5 feet away from the dragon and knocked prone. On a success, the creature takes half the damage and isn't pushed or knocked prone.