An American man has been charged with killing his wife on a cruise ship in US waters off Alaska.

His reason for doing so? "She would not stop laughing at me," he allegedly told witnesses at the scene.

On Thursday (July 27), 39-year-old Kenneth Manzanares was charged with the murder of his wife Kristy, also 39, aboard the Emerald Princess on Tuesday (July 25) night.

According to CBS News, the couple had been travelling with their children, as part of a large group, and were celebrating an anniversary. The incident arose from a dispute between the two.

Mrs Manzanares was found with a severe head wound and blood was all over the cabin where she was found, according to a federal search warrant affidavit.

Security and medical personnel from the cruise ship responded to the incident just after 9pm, where witnesses said Manzanares was found with blood on his hands and clothing.

He had grabbed his wife's body and dragged her towards the balcony, but the witness pulled her back inside the cabin by the ankles, according to CBS News.

Ms Megan Morr, another passenger on the cruise, said Manzanares had tried to jump off the ship but "security grabbed him before he could jump", reported Fox News.

Security arrived shortly after and the officer handcuffed Manzanares and held him in an adjoining cabin.

According to witnesses, the couple's three daughters were in the room when the incident took place.

Passenger Chris Ceman told CBS News he was in a room across from the Manzanares family, when "one of the little girls from that room came running out, calling for help, that her parents had been in a fight".

He said he sounded "pretty desperate" and that crew members responded as quickly as they could.

CBS News reported that the ship was carrying 3,400 passengers and 1,100 crew members.

It was on a seven-day round-trip cruise and had departed Seattle on Sunday (July 22). It left Ketchikan, Alaska, on Tuesday around 3pm, and the incident saw the ship diverted to Juneau, arriving just before 8am on Wednesday (July 26).

A check by The Straits Times showed that the Emerald Princess is part of the fleet of cruise company Princess Cruises, based in California. It is 290m long, which is almost that of three football fields, and has 19 decks.