How old do you have to be to get certified?

PADI requires you to be at least 10 years old to become a PADI certified Junior Open Water Scuba Diver.  10 and 11 years old must dive with a certified parent, guardian or PADI Professional. 12 to 14 years old must dive with a certified adult.  15 years old, the Junior certification upgrades to a regular Open Water Diver certification.