Octopus

Tiny beast | CR 0 | Darkvision 30 ft

Tentacle Attack// 5ft, +4 to hit. 1 bludgeoning. Target grappled till DC 10 escape. (tentacles occupied till then)

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.