The CDC has still not given cruise lines the technical information necessary for them to conduct test cruises, an integral part of conditional sail order, but Royal Caribbean International CEO Michael Bayley said it expected to those specifications "any day."

"We've been in regular communication with the CDC at the maritime unit and at the executive level," he said during a call with analysts to discuss the company's fourth-quarter earnings. "We're literally expecting the technical specifications any day soon. It's an intergovernmental process between several agencies within the government that are reviewing the technical specifications. They've assured us that as soon as all of these things come together they want to get us back into operations."

The test cruises are designed to show that a line is successful in mitigating the risk of Covid-19 spread to crew, passengers and communities.

Bayley said that more than 250,000 people had volunteered to go on those trial sailings as passengers. "So plenty of people are interested in cruising," he said.

"Our communication and dialogue with the CDC is productive," Bayley added. "When we have our discussions, it's a relatively open process, and as they've explained to us on many occasions, this really is about what's happening with the virus. They've assured us on several occasions that when these indicators really start move in a very positive way they'll start working with us to get us back into operations.

"And that's exactly what we're seeing now. Every single day I look at the [U.S. Covid case trend line] and it's just plummeting. My sense is we're getting closer and closer to good news."