Snorkeling is a lot of fun. It requires a lot less gear than scuba diving does and allows you to do many of the same things. You generally won't be able to go as deep and won't be able to stay underwater as much but it is still pretty good.
You will need some basic gear to get started. The absolute basics include a mask, snorkel, and fins. This will be enough to get you started. If you will be in colder water you may want a wetsuit or potentially even a dry suit. A wetsuit will also function as a life preserver keeping you afloat. If you are using a wetsuit you will need to weight belt to be able to dive under water. Otherwise you will just end up floating on top, which is fine if that is what you want.