Nearly a week after G.A.P. Adventures' Explorer sank in the Antarctic, the story of its final hours has been pieced together. We know that in the wee hours of the morning on Friday, November 23, the ship struck ice; the impact left a fist-sized hole in its ice-strengthened double hull. As water flooded the grinding engine room, the power failed. The expedition ship began listing, and passengers were called to their muster stations and lowered into the water on lifeboats.

We know that the captain and his first officer remained onboard at first to try pumping water out in an attempt to save the vessel; however, they eventually joined the other 52 crew members and 100 passengers in the survival craft to await rescue.

We also know that two nearby ships -- Hurtigruten's Nordnorge and Lindblad Expeditions' National Geographic Endeavor -- arrived on the scene, but Nordnorge had empty beds and so brought everyone onboard. Nordnorge later disembarked the evacuees at King George Island, from where they began boarding long flights back to Chile and, eventually, home.

With all safe and sound, however, we became interested in hearing the other side of the story: What happens at the bridge when a distress call comes through and a ship changes its focus from cruise holiday to dramatic rescue? What is it like to bring aboard a whole new rash of shipmates who are scared and cold? Cruise Critic was fortunate enough to swap e-mails and thoughts this week with Nordnorge Captain Arnvid Hansen and his crew about the anatomy of a rescue.

Cruise Critic: When did you hear about Explorer's accident and by what means?
Captain Arnvid Hansen and Team: Nordnorge received a call from National Geographic Endeavor, which had received a distress call from Explorer. The call came at about 2 a.m. local time on the morning of Friday, November 23.

CC: What was your immediate reaction?
AH: [We] set immediately toward the Explorer's position.

CC: How long does it take to decide a plan of action for a rescue?
AH: MS Nordnorge, as all ships in the cruise line's fleet, has routines in situations like this. In practice we do such operations with no delay due to planning. In this situation we had some distance to go before reaching the MS Explorer, so we could do some planning in advance.

CC: What are IMO (International Maritime Organization) regulations with regard to rescuing passengers?
AH: IMO regulations [are] clear. The rescuing of lives is top priority. Ship and material is secondary to life and health.

CC: Where and how did you board them on Nordnorge? How long had they been out in the tenders?
AH: The passengers and crew of Explorer were tendered at the scene. It was done by using the lifeboats of Nordnorge. We let down our lifeboats, helped the people onboard, and elevated the lifeboats again to the fifth deck of Nordnorge. They then had been in the lifeboats of Explorer for about four hours. Some of them naturally were cold, wet and hungry. We gave them dry clothing and warm meals, and made sure everybody was comfortable.

CC: Was the captain and first officer with you?
AH: Yes, we took onboard all the passengers and all crew from Explorer.

CC: How long were they onboard? How did you find room for them and did you have enough food onboard?
AH: We had our guests onboard for about 12 to 14 hours, until they were on shore at the Frei and Artigas bases at King George Island. Nordnorge had capacity both regarding cabins and food for our total number of people onboard. The atmosphere onboard was very good.

In a situation like this everyone is working together toward the same goal. The crew calmed down the passengers that had been put under some stress during the day. We have a nurse and a medical practitioner onboard, so we could if necessary provide medical help. [There were no injuries.]

CC: How did their arrival impact onboard ambience and schedule for your own ship?
AH: Our own schedule was delayed in some way because of the rescue operation, but at the time of the operation that is not a focus point. After setting the passengers and crew of Explorer ashore we took up our own original route.

CC: I know Nordnorge came to the aid of Nordkapp when it ran aground earlier this year. How was this situation similar -- or different?
AH: The incident with MS Nordkapp earlier this year can hardly be compared as a rescue operation. Neither the passengers nor the ship was in any danger at that time. Nordkapp was safely anchored and the passengers were never set in lifeboats. Nordkapp sailed under her own power to the harbor after the incident.

CC: What was the biggest challenge for your ship, officers, crew and passengers?
AH: We, both the officers and the crew, are well trained in this kind of rescue operation. We have drills on a weekly basis, and are extremely focused on our tasks when the operation is ongoing. Our first priority is to secure lives and health.

For our passengers, incidents like this do interfere with the planned program, but in spite of this we have never had complaints. Our passengers even sacrifice some of their own benefits if necessary. [This time around passengers offered up items of clothing to their new shipmates.] At sea, in a situation like this, everybody understands. It goes without saying, so to speak.

We've received dozens of e-mails from you on topics ranging from ship safety to global warming. We posed your frequently asked questions to industry experts. Here's what we learned:

What You Want to Know: What would have happened if help was a few days away?
What We Learned: Maritime is never a "few days away." Cruise ships generally don't go places far away from other ships as the nature of the industry is to compete for passengers (and in this case, Antarctica is seeing more and more ship traffic as the years pass). Even during rough weather, other ships -- including naval ships -- are able to get to the affected ship quickly.

WYWTK: I'm confused -- what's the difference between a single and double hull, and which is safer?
WWL: There's a common misconception (even here at Cruise Critic) that Radisson Diamond, now a casino ship, was one of the only cruise ships in recent history to have been built with a double hull. We just learned, however, that Radisson Diamond actually had a twin hull, which is something entirely different -- architecture with two bows, two sterns and two identical hulls separated by a center section raised in full or in part above the surface of the water.

So what is a double hull? Well, conventional ships with one bow and one stern are referred to as monohulls. A monohull can either have a single or double hull. While a single-hulled ship has one outer "skin," which could cause interior flooding if pierced, a double-hulled ship has an outer skin and a second parallel skin on the inside separated by air or some form of insulation. That way, if the outer skin is pierced, the inner skin prevents water from flooding a ship's interior.

But when it comes to safety, things aren't cut and dry. Mother Nature can pierce even a strengthened double hull and flood a ship, as we saw with Explorer.

WYWTK: Can a fist-sized hole really sink a ship? Were the water-tight compartments working?
WWL: G.A.P. Adventures' initial focus has been the well being of its passengers and arranging their onward travels. An investigation is ongoing, however -- and we'll continue to report information as it is released. Stay tuned to Cruise Critic News for the latest.

--by Melissa Baldwin, Managing Editor