You can start surfing as early as 5 years old, but it is often best to start at around the age between 7-9. However, just because you didn't start at that age, does not mean you can't surf!
There are certain surfing camps that have taught children as young as five years old. If they are going to be surfing at this young of an age, then it is important that they are either with an instructor or a parent who is an experienced surfer. If a five year old is confident enough to go out in the water and try surfing, then they by all means should be able to go try and learn on a small day. However, if he or she is being hesitant or is scared, it is important for the instructor or parent to not force the young surfer into trying it.
Younger surfers should learn at their own pace and never be forced to do something they are uncomfortable with. In sports like baseball and basketball it is okay to maybe show a bit of push in convincing a child to participate. In a scary sport like surfing, it is highly unnecessary to do that. A lot of young kids are afraid of simply going in the ocean, let alone hopping on a surfboard, therefore they should not be rushed into the sport.
While surfing is a sport that can be started at a young age, the great thing is that there is no limit to get started! You can start at 20, 30, 40, even 60 if you are up for it. Just because there may be people out in the water who have more experience than you, doesn't mean that you shouldn't be allowed to enjoy yourself like everybody else.