Amphibious. The turtle can breathe air and water.

Electrogenic Body. A creature that touches the turtle or hits it with a melee attack while within 5 feet of it takes 5 (1d10) lightning damage.

Stable. Whenever an effect knocks the turtle prone, it can make a DC 10 Constitution saving throw to avoid being knocked prone. A prone turtle is upside down. To stand up, it must succeed on a DC 10 Dexterity check on its turn and then use all its movement for that turn.

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

Electric Discharge (Recharge 6). The sähkö turtle discharges it's lightning. Each creature within ten feet of the turtle must make a DC 12 Dexterity saving throw, taking 22 (4d10) lightning damage on a failed save, or half as much damage on a successful one.