After almost 16 months, the cruise giants Carnival Cruise Lines and Royal Caribbean International were able to re-enter service over Independence Day weekend.Both Carnival Horizon and Freedom of the Seas departed from Miami.Carnival Horizon embarked on a six-day cruise from Miami to Amber Cove in Dominican Republic, and Half Moon Cay, a private Bahamian island.Carnival Vista left Galveston. Carnival Breeze departed Texas on July 15, and Carnival Miracle launched the Alaska season from Seattle on July 27.Mardi Gras, a new ship from Florida, will sail out of Port Canaveral on July 31, with other Carnival ships returning to service in August.Freedom of the Seas was the first Royal Caribbean ship to return to the US and welcomed passengers on three-night weekend and four night weekday trips to the private island destination Perfect Day at CocoCay in The Bahamas.Royal Caribbean strongly recommends that passengers aged 16 and over get fully vaccinated by 12 years or older before sailings departing August 1.Unvaccinated people or those who are unable to provide proof of vaccination must be tested and follow additional protocols. They also need to obtain travel insurance that covers any medical costs.Royal Caribbean plans to bring back nine additional ships by August. These include Anthem of the Seas (UK), Serenade and Ovation of the Seas (Alaska), and the new Odyssey of the Seas departing from Fort Lauderdale.In the coming weeks, the line will announce plans for reintroducing its entire fleet across the globe by the end the year.Christine Duffy, president of Carnival Cruise Line, stated that PortMiami was our number one homeport for passenger embarkations and ships. Today's return to cruising on Carnival Horizon is an important step in getting the company back in business and providing capital to thousands of workers who depend on the cruise industry to support their livelihood.It has been a difficult year, to put it mildly. I want to thank the state, PortMiami officials, as well as our business partners, for their support and patience throughout this challenging time.Michael Bayley, chief executive officer of Royal Caribbean International, said that there is much to be proud of. Families and their loved ones can now come together after being apart for more than a decade. We are welcoming them back to board to make up the time.It is fitting that Freedom of the Seas will be the first ship to welcome us back to the US, delivering the safe and memorable vacations Royal Caribbean is famous for. We are just beginning to see the return of summer family vacations.Celebrity Flora, one of Celebrity Cruises' three ships that will resume sailing the Galapagos archipelago has been operating. Celebrity Xpedition, which is for 16 passengers, will follow on July 24, and Celebrity Xploration, which is for 16 passengers.