Yet for the industry overall, there remains no comprehensive public database of events at sea like fires, power failures and evacuations. Neither the International Maritime Organization nor the United States Coast Guard track everything. But there is one unlikely man who does.

“It’s a Canadian professor of sociology,” Mr. Walker said, “who testifies in front of the senate.”

Ross A. Klein, an American with dual citizenship and a professor at Memorial University of Newfoundland in Canada, was a longtime cruise enthusiast, spending more than 300 days at sea between 1992 and 2002. During that time, he saw that there were differences between what the cruise industry was saying about environmental and labor issues, and what he was observing.

Today, Mr. Klein is an authority on the cruise industry, having testified at hearings before the House of Representatives and the Senate about onboard crimes, disappearances and industry oversights. His Web site, CruiseJunkie.com, is a record of fires, sunken ships, collisions and other events at sea over the last few decades that have been culled from news reports and sources like crew members and passengers. There are some limits: Mr. Klein receives fewer reports about incidents in Asia, Africa and South America, therefore most of the information is about cruises in North America and Europe. And he is unlikely to learn about problems that are not reported by English speakers or English language news organizations. “I’m sure there are a lot more incidents going on that we don’t know about,” he said.

I used the statistics Mr. Klein does have — many of which were part of his testimony last year before the Senate Committee on Commerce, Science and Transportation — to help determine just how rare (or not) the events aboard the Triumph were. Here’s what the data reveal.

Adrift at Sea Loss of power is common, according to Mr. Klein. “It’s inconvenient,” he said. But it typically lasts no more than a few hours.

Evacuation Evacuations are infrequent, and when they do happen, they are usually done safely. Mr. Klein said that about three or four times a year there is preparation to abandon a ship, though actually abandoning it is rare. One of the most recent evacuations was in 2007, when a GAP Adventures ship called the Explorer struck ice off Antarctica and began sinking. All 154 people on board were safely evacuated. Still, even larger evacuations in the ocean are possible: in 1999 a Sun Cruises ship caught fire and sank off the coast of Malaysia, but the more than 1,000 people on board safely made it onto lifeboats and rafts.

Fire Fires are not unusual. There have been about 79 fires onboard cruise ships between 1990 and 2011, according to Mr. Klein’s data. Up until about 2006 there were usually three or four fires a year. From 2006 onward the number of fires doubled to about seven or eight a year. That increase, Mr. Klein said, is the result of a combination of better reporting (thanks, social media) and the rapid growth of the cruise industry.