5e SRD:Giant Shark
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Huge beast, unaligned
Water Breathing. The shark can breathe only underwater.
Bite. Melee Weapon Attack: +9 to hit, reach 5 ft., one target. Hit: 22 (3d10 + 6) piercing damage.
A giant shark is 30 feet long and normally found in deep oceans. Utterly fearless, it preys on anything that crosses its path, including whales and ships.