Hold Breath. The psemareef can hold its breath for 1 hour.

Natural Camouflage. If the psemareef is fully submerged and does not move on its turn, it is considered hidden. A creature may use their action to make a Perception check against a DC of 14 to locate the psemareef. A creature with a passive perception of 14 or higher that is aware of the psemareef does not have to make this check.

Bite. Melee Weapon Attack: +6 to hit, reach 10 ft., one target. Hit: 14 (3d6 + 4) piercing damage.

Body Slam. Melee Weapon Attack: +6 to hit, one target. Hit: 16 (2d10 + 4) bludgeoning damage. If the target was an inanimate object, it takes two times the amount of damage. If the psemareef hits an object that a creature is standing on, that creature must make a DC12 Dexterity saving throw or else be pushed 5 feet away from the psemareef and be knocked prone.

Swallow. The psemareef makes a bite attack against a Small or smaller creature submerged in water. If the attack hits, the creature is swallowed. The swallowed creature is blinded and restrained, it has total cover against attacks and other effects outside the psemareef, and it takes 10 (3d6) acid damage at the start of each of the psemareef's turns. A creature reduced to 0 hit points in this way stops taking the acid damage and becomes stable.

The psemareef can have only one target swallowed at a time. If the psemareef dies, a swallowed creature is no longer restrained by it and can escape from the corpse using 5 feet of movement, exiting prone.