The U.S. Coast Guard has  suspended its search for a Carnival cruise passenger who inexplicably disappeared aboard the ship Monday.

According to WPLG, the Coast Guard used a MH-65 Dolphin helicopter and boats to search around 3,300 nautical square miles in surrounding Miami waters for 26-year-old Army veteran Kevin McGrath, who was last seen early Monday morning aboard the Carnival cruise ship Conquest.

McGrath’s sister said he was supposed to meet his family that same morning for breakfast but never showed, and was not among the passengers that deboarded at the Miami Port.

“We know that at 3:30 in the morning, he used the key card to get back in the room and anytime between then and 7:30 in the morning when he was supposed to meet my family for breakfast is when he went missing,” Kevin’s sister, Danielle McGrath, told ABC 25.

McGrath was last seen wearing a black shirt, black shorts and grey shoes. Cameras aboard the ship reportedly did not show McGrath going overboard and did not show him getting off the ship with other passengers.

“His SeaPass card was not scanned, because when you exit the ship, you have to scan your SeaPass card, and we had his documents, like his birth certificate and driver’s license, so there’s no way he could come off the ship,” Kevin’s father, Sean McGrath, told CBS 10.

“I was told from Carnival that they had sensors all around the ship, so if someone did go overboard, they would’ve been alerted, and nothing was alerted.”

Carnival said in a statement that McGrath was “not detected by surveillance systems, including U.S. Customs and Border Patrol during the debarkation process.”

“We’re hoping that his training and survival skills will come into play at some point,” Sean added. “We’re hoping, we’re hoping.”

McGrath is described as a Black male who stands 5 feet 9 inches tall, weighs 170 pounds, and has brown hair and brown eyes. He was last seen wearing a black shirt, black shorts and grey shoes