Hold Breath. The crocodile can hold its breath for 15 minutes.
Actions
Bite. Melee Weapon Attack: +4 to hit, reach 5 ft., one creature. Hit: 7 (1d10 + 2) piercing damage, and the target is grappled (escape DC 12). Until this grapple ends, the target is restrained, and the crocodile can't bite another target.
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.