Giant Octopus

Large beast, unaligned

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

STR: 17 (+3)
DEX: 13 (+1)
CON: 13 (+1)
INT: 4 (−3)
WIS: 10 (+0)
CHA: 4 (−3)

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.

Running this fight? Add the giant octopus to the initiative tracker: type its name and the AC, hit points and initiative bonus fill in, and the book button shows this stat block mid-fight.