He should be able to. A child 10-14 years of age can obtain a jr open water certification if the parent and instructor agree that the child is mature enough to digest the material and perform the skills. Once certified they are limited to a maximum depth of 40 feet and must be accompanied by a certified parent or guardian.
When the child is 15 they can take a scuba skills update ( 4 hour update class) and become a full open water diver and take as many continuing ed courses they desire (advanced diver, nitrox, stress rescue, etc.). The only thing is they cannot become a dive con/dive master or instructor until they 18.