In this file photo, under gray skies persons walk the upper deck of the Royal Caribbean Majesty of the Seas at the Port of Miami on May 14, 2020.

The U.S. Centers for Disease Control and Prevention gave its first green light for test cruises to Royal Caribbean Group Tuesday.

The cruise company will be able to conduct simulated cruises with volunteer passengers in late June to test out its COVID-19 protocols from PortMiami on its Freedom of the Seas ship. The test cruises are a requirement for ships that are not guaranteeing most passengers and crew on board are vaccinated against COVID-19 before revenue cruises can begin.

The approval is a significant step forward for the cruise industry, which has not been able to operate in the U.S. — its most lucrative market — since March 2020 after virus outbreaks and deaths on several ships.

Under a framework for restarting cruises first released by the CDC in October, cruise companies had to enhance COVID-19 testing capabilities on their ships, report weekly crew test results to the agency, and secure agreements with ports and local health authorities in the cities they plan to visit.

Royal Caribbean is the first company to have its agreements approved and move onto simulated cruises. The company will require all passengers who are 16 years or older to provide proof of vaccination when boarding, according to the company's website. Starting Aug. 1, the company will require all passengers 12 years or older to provide proof of vaccination.

Complicating the restart for companies in Florida is a law passed by the Republican-controlled state legislature and promoted by Governor Ron DeSantis that prevents cruise companies from asking passengers for proof of vaccination. The CDC recommends that all crew members, passengers and port workers be vaccinated when cruises restart. Cruise ships that can prove that 98% of their crew and 95% of their passengers have been vaccinated can skip test cruises and restart revenue cruises as soon as they have agreements with ports in place. Ships that don't meet the vaccination thresholds must first perform test cruises before getting approval to welcome paying passengers.

It is not clear how Royal Caribbean will require vaccination for passengers 16 years and older and comply with the Florida law for its cruises from PortMiami. The company did not immediately respond to request for comment.

Royal Caribbean Group is the second largest cruise company in the world with headquarters at PortMiami. The company owns three cruise lines: Royal Caribbean International, Celebrity Cruises and Silversea.