Multiattack

The kelp eel makes two attacks with its kelp tendrils, uses Reel, and makes two attacks with its slam.

Slam

Melee Weapon Attack: +8 to hit, reach 10 ft., one creature. Hit: 31 (6d8 + 4) bludgeoning damage.

Kelp Tendril

Melee Weapon Attack: +8 to hit, reach 50 ft., one creature. Hit: The target is grappled (escape DC 16). Until this grapple ends, the target is restrained, and the kelp eel can't use the same kelp tendril on another target. In addition, at the start of the target's next turn, it begins to suffocate as the eel's grip crushes the breath out of it.

Reel

The kelp eel pulls each creature grappled by it up to 25 feet straight toward it.