Hold Breath. While out of water, the octopus can hold its breath for 30 minutes.

Underwater Camouflage. The octopus has advantage on Dexterity (Stealth) checks made while underwater.

Water Breathing. The octopus can breathe only underwater.

Tentacles. Melee Weapon Attack: +4 to hit, reach 5 ft., one target. Hit: 1 bludgeoning damage, 2 necrotic, and the target is grappled (escape DC 10). Until this grapple ends, the octopus can't use its tentacles on another target.

Ink Cloud (Recharges after a Short or Long Rest). Shoots a stream of viscous black liquid up to 15 ft. target must roll a dex save of 13 or take half damage. 1d6 necrotic damage and target has disadvantage on any rolls requiring sight.