Perched on the deck, a helicopter opened its doors and medics evacuated a wounded Haitian on a stretcher. Then another, and another, and then a fourth.
Since its arrival, this huge US naval hospital ship has seen non-stop action. Patients have come in with multiple fractures, head injuries and gaping wounds.
In the main treatment room of the ship, which arrived here Tuesday evening, patients bore the sad scars of the January 12 quake, which killed at least 110,000 people and injured some 250,000, according to Haitian government figures.
A little girl with her leg in plaster and her left arm in a splint lay in one bed, emaciated, next to a stuffed toy fox. In the next bed, a group of doctors had gathered around a woman trying to help her breathe.
Two beds down, a young man's feet protruded from his blanket. As a doctor manipulated them, the survivor cried out in pain.
"We received 221 patients since Tuesday," said ship spokesman Lieutenant Bashon Mann, adding that about half of the patients were children.
This is just the beginning of the mission for the USNS Comfort, a white ship adorned with red crosses, which travelled to Haiti's shore from Baltimore, Maryland to help a massive international relief effort.
Haiti's health ministry has taken charge of designating the most serious cases for transfer to the ship for treatment.
"We are receiving a massive amount of people. It never stops, hour after hour. We are anticipating to receive them weeks after weeks and even months," said Commander William Todd, a pediatric orthopedist.
Clearly exhausted, Todd told AFP that the ship was accepting people with some of the gravest injuries from the massive 7.0-magnitude quake.
The US vessel offers the families of patients lodging on board the ship but "a lot of people are coming alone because they've lost so many," he said.
The Comfort has around 1,000 beds, six operating rooms and the most modern medical equipment, making it ready to deal with everything from minor injuries to complex operations.
"Many of them are coming in because their wounds got infected," said Todd.
"You have a lot of injuries that can become life threatening without proper attention because it allows for infection and gangrene to come in and that results in the loss of limbs and even in the loss of life."
But Todd said he had seen plenty to be hopeful about too, particularly with some of his youngest patients.
"The beautiful thing about children is the fact that they all are very adaptive and before you know it they're just going like nothing ever happened," he said.
Despite Todd's optimistic tone, a grim reality has settled over the ship.
On the deck, the steady stream of medical evacuations continued, bringing new patients to the ship, including one with her arm in a sling.
With her safely aboard, the SeaHawk helicopter that delivered her took off again.
By noon, some 40 patients had landed on the deck of the Comfort, which is surrounded in the sea off Haiti's coast by a half-dozen US war ships, pressed into service as part of the massive US military deployment to the Haiti relief effort.
Though assistance has poured in from around the world, the magnitude of the task remains enormous, and the United States is planning to send another hospital ship, the Mercy, to Port-au-Prince to help.