What is a Sit-on-Top?
There are two broad categories of kayak.  The traditional sit-in variety of kayak with a cockpit to sit in, and the 'sit-on-top' style of kayak.  As the name would suggest, the paddler sits on top of the 'sit-on-top' kayak rather than inside a cockpit.  Sit-on-top kayaks have scupper holes which means they are self draining, if water comes into the kayak it will quickly flow out through these scupper holes - in other words you can't be swamped.
Sit-on-top kayaks are very stable, easy to paddle, safe and lots of fun.  They are now a very popular class of kayak on the market.
Basically hop on and paddle, its as easy as that, no training is required. 
There are sit-on-tops designed for surfing, family fun, touring, fishing, fitnesss training, diving and kids' recreation. It is accessible (to a wide range of paddlers, young and old, small and large) so the fun you have can be as serious or as lighthearted as you like.