Plenty of great suggestions here. As a parent of young children myself, to me, the one mandatory activity any child should take is swimming. It not only teaches that person a life long "respect for the water", but when she/he gets older, they'll be going to swimming pools, lakes, etc. with family and/or friends. To be able to competently swim and to understand the proper dos and don'ts, it ensures not just that she/he will have a good time, but that they will exercise proper judgement and be safe.
As for other sports, I know that this is not local to OP's area, but in my local area, there is something called Dash Sports, where it is a multi-sport activity in a non-competitive environment where children can play a whole variety of sports without all the pressures that come with being in organized leagues. All of that stuff will come in time of course, so there's no rush to get them into that kind of environment. Plus, your child will probably have one or two sports that she/he will like more than others, and that will be drawn out without any pressure on them.
Here is the link to take a look at to give you a flavor of what I am talking about.
http://www.dashsports.ca/
I'm sure there's something like that in your local area. Hopefully this is helpful.
