Welcome to ScubaBoard!
Don't forget to fill out your profile, so that we can add context to your future posts. Also, once we know where you are geographically, you may find that you'll have a whole bunch of new dive buddies to choose from in the future.
If you are going to be in Kauai when you get certified you may want to post your question in the
Hawai'i O'Hana forum. They will be able to point you to some dive shops that can certify you.
If you are located somewhere else when you get certified (like here in SoCal, the name of this forum) you may want to let us know what part of the region you are in, so that we can better direct you with information specific to your area.
Depending on when you are going to Kauai, you may want to get certified before you go. This way you are sure to have gotten the initial learning out of the way and will be able to just go diving while you are there.
Also, keep in mind that diving can be a dangerous sport requiring a mature thought process. When your 10-year old son is learning, he will be relying on you to make the right decisions when he is uncertain. So for your safety and that of your son, make sure that you learn as much as you can about diving.
I've been having this same conversation with a good friend of mine who is contemplating learning to dive with his 14-year old son.
Some people on this board will tell you that these kids are too young and others will show you example of kids who have learned at an early age and done just fine. Personally, I think it depends on the individual.
I hope this post gets you on the right track. Learning to dive is a bit more complicated than strapping on a tank and jumping in.
Dive safe!
Christian