Tom_Kline - So when you go down for a dive the snorkel fills with water which you then blast out of the tube? Can I get any snorkel or does it have to be some special kind of snorkel? I remember those snorkels we used as kids, they didn't seem advanced in any kind of way.
Yup, once one returns to the surface one just does a quick exhalation and the water squirts out, much easier to do than write down!
There are a huge number of snorkel models - some have do-dads to make clearing a bit easier. Each of the major scuba manufacturers has a range of models. Here is an example of one from Scubapro:
You can read the description. You will typically be taught how to use a snorkel during the first pool session of a scuba. The instructor might have different models for you to try out or they may require you to buy one first. I would avoid a super cheap one as you may find yourself replacing it it sooner than later.