President and CEO of Norwegian Cruise Line Holdings, Frank Del Rio said the changes were long anticipated.
"Our long-awaited revisions to our testing and vaccination requirements bring us closer in line with the rest of society, which has learned to adapt and live with Covid-19, and makes it simpler and easier for our loyal guests to cruise on our three best-in-class brands," he said in a statement this week.
NCL's SailSAFE programme would still be across ships for the foreseeable future, but would continue to be revised "as the public health environment evolves".
From September 3 fully vaccinated passengers would be able to sail without a pre-departure Covid-19 test.
While Norwegian brands are the first US-based ships to allow unvaccinated passengers back onboard, it is reflective of a wider trend.
This month Carnival Cruise Lines, MSC and Royal Caribbean all relaxed testing requirements for vaccinated guests on short itineraries.
Virgin Voyages has eliminated pre-boarding tests entirely for vaccinated cruisers.
This comes a month after the US Centres for Disease Control and Prevention officially ended its pandemic-era edicts on cruise ships, allowing the Conditional Sail Order to lapse in July.
It continues to advise travellers booking cruise travel to be fully "up to date" with vaccinations.
In New Zealand passengers arriving via international cruise ships will still be required to be fully vaccinated, as per the New Zealand Traveller Declaration. However the official guidance is that passengers arriving via the maritime border will not need to complete a Covid-19 test on arrival.
"On the advice of public health officials, asymptomatic travellers arriving on cruise and recreational vessels will not need to self-test after arriving."
Vaccine requirements on domestic sailing itineraries will be set by cruise operators.
Tomorrow sees the first passenger cruise arrive in New Zealand since the reopening of the maritime border, last month
P&O's Pacific Explorer is due into Auckland's Waitematā Harbour at 7.30am tomorrow, August 12, as the first cruise ship in more than two years. P&O still requires guests to be fully vaccinated, with their latest dose at least 14 days before embarking.