As divers continue to hunt for survivors of the Sewol ferry in waters off South Korea’s coast, questions remain unanswered. Why did the captain abandon the ship and leave the steering in inexperienced hands? Why weren’t people evacuated earlier? While those questions likely won’t be answered until an investigation is complete, we’re also wondering: Exactly how safe are ferries, anyway?

The answer depends largely on where you are. In developing countries where ferry travel is common, such as Bangladesh, Indonesia, and the Philippines, a number of factors combine to make that mode of travel more dangerous than it is in the United States or Europe. Most of the worst ferry accidents have occurred in such countries, each killing hundreds to thousands of people.

“There are four major causes of [ferry accidents] in developing countries,” said Roberta Weisbrod, executive director of the Wordwide Ferry Safety Association. “Poor quality vessels, overcrowding, sudden hazardous weather, and, universally, the human factor.”

Unlike cruise ships, ferries have to contend with how to stow large cargo so that it will balance the boat. The loud noise many reported hearing on the South Korean boat may have been caused by large cargo coming loose, experts said.

Eight Unbelievable Cruise Ship Disasters

Add in the popularity of ferry travel and the large populations of those countries, and the risk understandably rises. It’s a big enough problem that an organization called InterFerry and the International Maritime Organization launched the Ferry Safety Project in 2006, focusing on the countries where ferry travel is most common and most dangerous, with a goal of reducing ferry accidents by 90 percent.

The 2003 Staten Island Ferry crash in the U.S., by contrast, killed 11 people -- and that was the worst accident in recent history, Weisbrod said. In Europe, there were 147 accidents involving passenger vessels in 2010 -- but only seven fatalities (which could imply that the accidents were less serious or that the response was better).

The Ferry Safety Project has made great strides in training captains and crews, Weisbrod said. Still, accidents will always happen, so the response is also critical in reducing fatalities.

“The Titanic was the first recorded massive search-and-rescue event,” said Bruce Reid, CEO of the International Maritime Rescue Federation. “And people thought that [it was so safe that] it was never going to sink, that there was no way it could go under. Even though we work hard to improve safety standards, there’s always the risk of an accident.”

However, since accidents are so few and far between, preparing for them is challenging.

World's Most Dangerous Oceans Identified

“We can prepare through planning and practices and trials, but what actually happens when you’re on the water is when you really learn,” Reid said.

Coordination of a large-scale search-and-rescue effort is key, he said. Linking nearby boats (vessels of opportunity), helicopters, the local coast guard, rescue boats, medical teams and shore side response requires advanced logistics. And when time is not a luxury, and sea conditions are not cooperating, it pushes the importance of working together.

“The massive complexity of a mass search and rescue is that there are multiple layers of infrastructures that may not have worked together in the past,” he said.

Still, despite tragedies like this week’s, ferries may be more dangerous than air or train travel (there were 4,000 ferry accidents worldwide between January 2000 and March 2004), but they’re still as safe or safer than driving a car.