Sperm Whale

Sperm whales are the most powerful hunters amongt the whales, and travel in pods of 3 to a dozen individuals. Although they hunt any prey smaller than them, they have a special appetite for smaller krakens and other soft bodied creatures of the deed.
Despite their ferocity, they are the favored target of whalers because of the oil contained in their massive heads, which produces a bright, white, smokeless flame.
The whales are not helpless, however, and often breach the water to capsize whaleing vessels or simply ram the hull. Many ships have been lost this way.

Sperm Whale CR: 10 (5,900 XP)

Gargantuan beast, unaligned

Armor Class: 15 (Natural Armor)

Hit Points: 198 (12D20 +72

Speed: , swim: 50 ft

STR

26 +8

DEX

8 -1

CON

22 +6

INT

4 -3

WIS

12 +1

CHA

5 -3

Saving Throws: Strength +11, Constitution +9

Skills: Athletics +11, Perception +7

Damage Resistances: Cold

Senses: blindsight 120ft., darkvision 120ft., passive Perception 17

Challenge Rating: 10 (5,900 XP)

Hold Breath. The sperm whale can hold its breath for 2 hours
Echolocation. The whale can't use blindsight while deafened
Keen Senses. The sperm whale has advantage on Wisdom (Perception) checks relying on hearing or sight
Siege Monster. The killer whale deals double damage to buildings and structures.

Actions

Multiattack. The whale can make two attack actions: one with its bite and one with its tail. It cannot make both attacks against the same creature on the same turn.
Bite. +11 to hit:, 10ft., , one target. Hit 25(3d10+8) piercing damage. If the target is size Large or smaller, it must succeed a DC 19 Strength saving throw or be swallowed by the whale. A swallowed creature is restrained and blinded and has total cover against attacks and other effects outside the whale and takes 10(3d6 acid damage) + 10(3d6 bludgeoning) damage at the start of each of the whale's turns. If the whale takes damage, it must succeed a Constitution saving throw with a DC equal to half the damage dealt by the swallowed creature(minimum 10.) On afailed saving throw, the whale regurgitates all swallowed creatures which fall prone in a space within 10ft. of the whale. If the whale dies, a swallowed creature can escape from the corpse by using 20ft. of movement exiting prone.
Tail. +11 to hit:, 10ft., , one target. Hit 28 (3d12+8) bludgeoning damage. If the target is a creature, it must succeed a DC 19 Constitutions aving throw or become stunned until the end of its next turn.
Sonic Burst(Recharge 5-6). Creatures within a 120ft. cone must succeed a DC 19 Constitution saving throw or vecome stunned for one minute. It can repeat its save at the end of each of its turns to end the effect.