After at least a dozen drownings or near drownings on cruise ship pools in the past several years, three major cruise lines now have lifeguards on duty.

Norwegian Cruise Line is the latest to add lifeguards, announcing recently that the line would roll out guards at family pools beginning this summer on its largest ships — Norwegian Escape, Norwegian Getaway, Norwegian Breakaway and Norwegian Epic. The remainder of the Miami-based line’s fleet will have lifeguards by early 2018.

Norwegian will also begin offering complimentary swim vests for adults and children, which it hopes to offer across all its ships by this summer, said NCL spokeswoman Vanessa Picariello.

The line has stationed deck attendants who are certified in first response on its four mega ships since 2015, said Andy Stuart, president and CEO of NCL, in a statement, but will now add dedicated lifeguards.

“While parents are always the first line of supervision when it comes to water safety, we felt it was important to provide this added measure across our fleet,” Stuart said.

The announcement comes two months after Royal Caribbean International also decided to start posting lifeguards at every pool, including in the adults-only Solarium area. The change began in February with the Oasis of the Seas; all remaining ships in the line’s fleet will have lifeguards by June.

Miami-based Royal Caribbean is partnering with IAM StarGuard Elite, which will provide licensed lifeguards, consulting and risk-prevention services. The lifeguards, who will wear red-and-white uniforms, will not serve other roles on the ship, as often is the case with crew members who take on various tasks on cruise ships. The line also will offer a 15-minute water safety presentation during the embarkation-day open house session for Adventure Ocean, Royal Caribbean’s youth program.

Royal Caribbean began offering life jackets for children to use in the pool in late 2015.

Until the dual announcements this year, Disney Cruise Line had been the only line to offer lifeguards. The change was prompted by a March 2013 incident when a 4-year-old nearly drowned in a pool aboard the Disney Fantasy and suffered a brain injury, resulting in a multimillion-dollar settlement and lifeguards on all Disney ships.

The lack of lifeguards on cruise ships (which instead stress parental supervision), a practice that hotels also follow, has become an increasingly contentious issue after multiple drownings, most of them involving small children, on ships from the major cruise lines.

Last summer, an 8-year-old boy drowned on Royal Caribbean International’s Anthem of the Seas. The year before, a family sued the line, demanding that it add lifeguards at pools after a 4-year-old nearly drowned in a wave pool on Oasis of the Seas. In 2014, a 6-year-old boy suffered a brain injury after nearly drowning on Independence of the Seas.

Three children aboard Norwegian Cruise Line ships have drowned or nearly drowned. In May 2015, a 10-year-old girl drowned on the Norwegian Gem and in February 2014, two children were found in a pool on the Norwegian Breakaway. A 4-year-old boy died, and his 6-year-old brother was airlifted to the hospital in critical condition.

In 2013, a 6-year-old boy from Orlando drowned aboard Doral-based Carnival Cruise Line’s Carnival Victory. That same year, a 41-year-old man drowned in a hot tub on the Carnival Dream.