One of the best things about snorkeling is how little equipment you actually need to have a good time.  You'll only need a comfortable set of fins and a properly fitting mask with snorkel.  Optional gear includes a underwater GoPro cameras, a thin wetsuit, and some flotation assist devices depending on your needs.

The Essentials:

Snorkeling Masks - This is your window to Hawaii's underwater paradise.

Snorkels - They named the activity after it, so you know its important.

Snorkeling Fins - Make it easy on yourself.  Be comfortable and swim efficiently.

Sunscreen - This is because you want to enjoy your entire vacation right?

Should I Buy or Rent My Snorkeling Gear? - Find out what's best for you.