Keen Smell. The sea troll has advantage on Wisdom (Perception) checks that rely on smell.

Regeneration. The sea troll regains 10 hit points at the start of its turn. If the troll takes acid or fire damage, this trait doesn't function at the start of the troll's next turn. The troll dies only if it starts its turn with 0 hit points and doesn't regenerate.

Aggressive. As a bonus action, the Troll can move up to its speed toward a hostile creature that it can see.

Amphibious. The sea Troll can breathe air and water.

Multiattack. The troll makes three attacks: one with its bite and two with its claws.

Bite. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 10 (2d6 + 4) piercing damage.

Claw. Melee Weapon Attack: +7 to hit, reach 5 ft., one target. Hit: 13 (3d6 + 4) slashing damage.