Blood Frenzy. The shark has advantage on melee attack rolls against any creature that doesn't have all its hit points.
Water Breathing. The shark can breathe only underwater.
Actions
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.
RollQuest ships the D&D 2014 SRD as a content pack, on a 5e character sheet that does the maths - roll from the sheet and let the numbers work themselves out. Free to start.