Amphibious. The dragon can breathe air and water.
Bite. Melee Weapon Attack: +6 to hit, reach 15 ft., one target. Hit: 9 1d10+4 piercing damage plus 5 1d8 force damage. Steam Breath (Recharge 5–6). The dragon exhales water and steam in a 60-foot cone. Each creature in that area must make a DC 13 Constitution saving throw, taking 17 3d10 fire damage on a failed save, or half as much damage on a successful one. Being underwater doesn't grant resistance against this damage.