Exterior shot of Norwegian Sun at sea

(9:47 a.m. EDT) -- Norwegian Cruise Line is giving passengers who sailed on Norwegian Sun's last cruise before it entered dry dock -- a Panama Canal crossing -- a future cruise credit in the amount of their fare paid after numerous complaints that it was essentially a "construction zone."

According to Norwegian Cruise Line, which said the construction was part of its "continuous efforts" to ensure consistency across its fleet, the line does its "utmost to minimize any impact to our guests when these enhancements are being implemented, we do recognize that during a recent sailing, we did not meet the expectations of our guests, nor our own standards, for which we truly apologize."

As compensation, the line, which originally offered a 25 percent future cruise credit, is now offering a full 100 percent future cruise credit worth their fare paid. The credit can be used on any Norwegian Cruise Line sailing from now through March 31, 2023.

"We realize this cannot replace their recent experience but do hope to have the opportunity to welcome them on board again soon."

Reports of closed venues, toxic fumes, construction noises, and health issues began to emerge just days into the 15-night cruise.

"Access to public space is severely limited," wrote Cruise Critic member Ozcruiser28 on the Cruise Critic Norwegian Cruise Line forum. "Decks we can access are filled with toxic fumes and dust. Many passengers are suffering from eye irritations. Ship is dirty and unsafe."

While it is not uncommon for construction to begin on a ship prior to dry dock, pictures on the "Panama Canal Sun" Facebook group started by some of the most upset passengers do show the pool deck ripped apart as well as other venues closed off.

"As one of the passengers on this cruise, I'd like to reiterate the deplorable conditions we unknowingly faced upon setting sail," wrote Cheryl Roberts Gale. "On the third day of the cruise, I went to walk the jogging track around deck six, only to find it closed off halfway around. While walking back and fourth [sic] between the ropes, I watched as construction workers with masks dealt with chemicals and what looked like a hot glue or tar substance. Naturally I was wondering why I wasn't handed a mask… Much of deck six was closed off for the remainder of the cruise which was really inconvenient for those of us that like to job. Similarly, the top deck of the ship was open the first day and then closed off for the remainder of the cruise with lots of drum style containers containing chemicals."

But not all passengers agree the cruise was as bad as reports are making it out to have been.

"We were on the Norwegian Sun for this cruise. While there were a few inconveniences, it was not the end of the World and the Sky did not fall," posted Bill Antonucci to the same Facebook group. "We did not pay much attention to the work in progress and concentrated on enjoying the rest of the ship… While the work should have been disclosed before the ship sailed, it was restricted to certain areas of the ship and in most cases not much of an inconvenience…"

Norwegian Sun will come out of dry dock on April 19, with another Panama Canal transit. It will begin sailings to Cuba from Port Canaveral on May 7.

Sailings that take place on cruise ships both before and after dry docks occasionally face issues with construction, which is why Cruise Critic notes that cruises can be affected by the changes. For more, read What to Expect: Cruising Before or After a Dry Dock and What is a Cruise Ship Dry Dock?.

--By Dori Saltzman, Senior Editor