The U.S. Navy currently operates two hospital ships dedicated to providing emergency care to sick and wounded soldiers.

Comfort and Mercy
The two naval hospital ships are called USNS Comfort and USNS Mercy. The ships are operated by the Military Sealift Command and are crewed by a staff of civilians.

Each ship is classified as "non-commissioned." In keeping with the Geneva Convention, the crew onboard the ships do not carry any weapons and firing on the vessels is considered a war crime.

Both the USNS Comfort and USNS Mercy contain 12 fully equipped operating rooms, and 1,000 hospital beds. Other features of the hospital ships include a morgue, pharmacy, medical labs, dental facilities, and the latest medical technology – including CAT scan and MRI machines. The ships also have helicopter landing pads and side ports that allow wounded soldiers to be offloaded onto the vessels by boat.

Converted Oil Tankers
USNS Marcy entered service with the U.S. Navy in 1986, and USNS Comfort has been operational since 1987. When not in service, the ships are docked in Baltimore, Maryland or San Diego, California. Each ship is a converted oil tanker.

Specifically, they are converted San Celmente-class super tankers. Each hospital ship can be up and running with a full crew in less than a week.

Although the HSNS Comfort and HSNS Mercy are used primarily to help injured and ill soldiers, the ships are also used to aid in disaster relief and humanitarian missions around the world. The HSNS Comfort was deployed to Haiti in January 2010 to help that country after it was rocked by a devastating earthquake.