Shelby, this might be what you are looking for, I have not personally taken this excursion, but my Sis-in-law and her family took it and really enjoyed it. You can find the information on the Carnival.com site:
Find paradise on a private, secluded island surrounded by white sand beaches and pristine crystal clear water.
On this excursion you will:
Find out why world famous Blue Lagoon is Nassau’s most popular tour destination.
Begin from the Prince George Dock aboard the Calypso or one of her sister ships.
Depart with a complimentary island beverage in hand, on a scenic cruise to Blue Lagoon.
Have the opportunity to rent aqua cats, tubes and paddleboats.
Bask in the sun, listening to the live Calypso band and swim in the sea.
See “The Tiger”, Blue Lagoon’s own spectacular limbo dancer.
Enjoy the Sea Garden grill restaurant, featuring a full lunch and beverage menu at reasonable prices.
Use the island’s modern amenities such as fresh water showers, changing facilities and bathrooms.
Enjoy a relaxing scenic boat ride back to the ship at the end of your day.
Note: If you purchase this excursion with snorkel equipment, it will be provided for you on the island.