Giant Octopus

Large beast, unaligned

Armor Class 11
Hit Points 52 (8d10 + 8)
Speed 10 ft., swim 60 ft.

Skills Perception +4, Stealth +5
Senses darkvision 60 ft., passive Perception 14
Languages —
Challenge 1 (200 XP)

Hold Breath. While out of water, the octopus can hold its breath for 1 hour.
Underwater Camouflage. The octopus has advantage on Dexterity (Stealth) checks made while underwater. Water Breathing. The octopus can breathe only underwater.

Actions

Tentacles. Melee Weapon Attack: +5 to hit, reach 15 ft., one target. Hit: 10 (2d6 + 3) bludgeoning damage. If the target is a creature, it is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the octopus can’t use its tentacles on another target.
Ink Cloud (Recharges after a Short or Long Rest). A 20- foot-radius cloud of ink extends all around the octopus if it is underwater. The area is heavily obscured for 1 minute, although a significant current can disperse the ink. After releasing the ink, the octopus can use the Dash action as a bonus action.