This is an excursion you can take while your cruise ship is in port and it's not just Disney Cruises that has a relationship with this independent company...it's not owned or operated by Disney.

Royal Caribbean: Captain Nautica Mini Boat Excursion
"Overview: Pilot your own mini-boat on a St. Thomas snorkeling tour to the enchanting underwater world of Christmas Cove. Follow your guide through crystal-blue waters on the south side of St. Thomas. Then swim and snorkel in a protected marine habitat alive with tropical fish. Guides will help you climb back onboard for the boat trip back. Relax afterwards with a freshwater rinse and rum punch or fruit juice. Ride a safari bus back to pier."
http://www.royalcaribbean.com/shoreExcursions/product/detail/view.do?sourcePage=shorexByPort&ProductCode=STI3&DestinationCode=

Website: Captain Nautica Excursions
"Captain Nautica provides the most fun and exhilarating boat rentals in the Virgin Islands. Our 41’ Bravo speedboat can get you to all the islands and the best USVI snorkel spots in comfort, speed and class! Our boat rentals are stocked with drinks and the smooth ride allows us to reach spots that other companies simply cannot go!"
http://www.viwatersports.com/

Facebook page: Captain Nautica
"We offer snorkeling tours, rental boats, private charters and speed boat rides in beautiful St Thomas, US Virgin Islands and the British Virgin Islands."
https://m.facebook.com/captainnautica

Captain Nautica
"Captain Nautica provides the most fun and exhilarating private charters in the Virgin Islands. We offer private charters for up to 12 people in both the US and British Virgin Islands."
https://www.tripadvisor.ca/Attraction_Review-g147404-d1218364-Reviews-Captain_Nautica-St_Thomas_U_S_Virgin_Islands.html   https://www.islandeguide.com/listing/captain-nautica-charter.html

Captain Nautica Saint John Expedition
https://youtu.be/noXbYx_lJ8Y