Norwegian Cruise Line Holdings foresees a full return of its entire fleet of 28 ships by as early as May of next year, despite dozens of conditions laid out by the US Centers for Disease Control and Prevention's (CDC).

Two weeks ago the CDC lifted its no-sail order for cruising in US waters but issued a list of 74 recommendations that include onboard Covid-19 testing labs and simulated voyages.

"My best sense today, given all the uncertainty we have to work out with the CDC and when we can start, is six to nine months," chief executive Frank Del Rio said on Tuesday during an earnings call with analysts.