Cruise lines continually reinvest profits into the fleet. Whether upgrading onboard amenities, booking the latest and greatest talent acts, or adding new destinations to their itineraries, the cruise industry is rarely stagnant. However; how often are companies spending money to upgrade safety measures? Surprisingly, not as often as you’d think.

In the last two months of 2018, five people died after falling overboard from cruise ships. According to a report from Time with statistics dating back to 2010, the industry averages 21 of these incidents during a given year. While cruise lines such as Carnival install onboard roller coasters, experts say only a small number of companies equip ships with modernized man overboard systems to alert the crew when a person falls off. Some cruise line officials tend to place blame on passengers involved in such accidents, and others believe existing safety measures are enough.

“All of our ships have man overboard cameras and for several years now, our company has been testing man overboard alarm systems,” said a Carnival Cruise Lines spokesperson while speaking to Quartz. “Historically these systems have been unreliable, generating a significant number of false alarms. The technology has been gradually improving, and we continue to actively test it on our vessels.”

Other cruise lines have echoed Carnival’s sentiments. Royal Caribbean (RCL) officials stated in a press release,”While RCL desires a better way to identify a person going overboard, to date, no man-overboard detection system has shown to perform reliably enough for wide-scale deployment.”

Under the Cruise Vessel Safety and Security Act, as long as a ship is outfitted with video surveillance of the railings, a man overboard detection system isn’t required. With an average price tag of at least six figures, cruise lines have little reason to invest in these systems. Jim Walker, a maritime lawyer and creator of Cruise Law News, said during an interview with Time, “The legal consequence of losing a passenger on a ship is inconsequential to the cruise industry.”

Still, cruising remains a relatively safe way to travel. Tens of millions of people cruise around the world each year, and man overboard incidents are rare. Cruise lines also experienced a decrease in the number of infectious disease outbreaks in recent years.