look into island hopping to. Flights are like $49 I think.

For touristy snorkeling, there is the half moon island off the coast of Maui, there are 2 nice spots on the big island (doing all those, that's how I know of them)

Maui one
http://maui-activities.net/reservati...age=1&island=2

That site also has many activities to do on Maui.