Orca

Around ice, reefs and small boats, an orca's intelligence is as dangerous as its size. It studies movement, strikes from below and uses waves or its own body to separate prey from safety. Pods teach successful methods to their young, so an orca that has learned how a hull, seal hide or fishing net works may exploit that knowledge repeatedly. It may test an unfamiliar object before committing to the attack that breaks it.

Breach and Crush: bludgeoning, melee 5 ft, +4 to hit, 2d10+4. A swimmer or creature on ice makes a Quick save; on a failed save, it is driven 15 ft through the water or thrown from the ice. A canoe-sized boat instead takes the damage directly.

Echolocation: darkness, murky water and ordinary invisibility do not conceal a moving creature within 60 ft. Loud overlapping noise forces the orca to make a Mind save; on a failed save, Echolocation fails until the end of its next turn.