Take the Mushi/Mushi catamaran snorkel, great snorkeling, great catamaran, great crew. Just about anywhere in Bonaire is fantastic diving/snorkeling. Right across from the dock is a nice little bar/restaurant.
You might want to have a look at the website of the Aquaspace. It's a semi-submarine sail charter that used to sail around Bonaire for years. It has been away for awhile, but is now back:
Edited to remove advertising link.