Florida green watersnake (Nerodia floridana) is a harmless North American species of water snake. N. floridana is the largest and most dominant watersnake in North America. Fully grown it will reach 30-55 in (76–140 cm). Its coloration is solid greenish-brownish with whitish belly in adults. Juveniles have about 50 dark bars down their dorsum and on their sides, which fade gradually with age.