Decide which tour company to snorkel with. Different companies have different prices and inclusions. For example, Crystal River Tour has packages that allow you to see both manatees and river dolphins, and the tours last from one to three days. You can also visit Americanprodiving.com, Riverventures.com or Snorkelwithmanatees.com.
Purchase your tour after deciding which one appeals to you. The tour company may have additional items for purchase or rental, such as snorkeling equipment or underwater cameras.
Be aware of the company's refund and cancellation policies. Confirm your tour with the company after purchasing, or as the company requests. They likely will require additional information, such as your height and weight and the heights and weights of others in your party.