Unlike airlines that require passengers to get either vaccination or at least have a negative COVID-19 test, Royal Caribbean's June sail from Nassau, in the Bahamas, requires all adults to be vaccinated before entering the vessel. However, there's an exception, children under the age of 18 with a negative COVID-19 test are allowed to board. 

The good news for Americans seeking the vaccine, President Joe Biden stated last week he wants vaccines available to all Americans by May 1. 

Michael Bayley, president and CEO of Royal Caribbean International, who was quoted by USA Today, said the cruise liner is excited to finally have a vessel sail in the Caribbean "gradually and safely."

"The vaccines are clearly a game-changer for all of us, and with the number of vaccinations and their impact growing rapidly, we believe starting with cruises for vaccinated adult guests and crew is the right choice," Bayley said. 

Royal Caribbean also announced its sister line, Celebrity Cruises, will begin sailing on June 5. The Celebrity Millennium will sail from St. Maarten on a week cruise with vaccinated crew and passengers, except passengers under 18 must have a negative test. 

"Returning to the Caribbean ... marks the measured beginning of the end of what has been a uniquely challenging time for everyone," said Lisa Lutoff-Perlo, CEO of Celebrity Cruises, a division of Royal Caribbean, who Reuters quoted.