SAN DIEGO -- For the crew of the U.S. Naval Hospital ship Mercy, Thursday will definitely have a feel of "been there and done that."

On Thursday, the USNS Mercy will deploy for another humanitarian mission to areas in the Pacific in desperate need of medical care.

The crew of the Mercy said they cannot wait to depart.

Like any other ship getting ready for deployment, supplies need to get aboard.

But for the Mercy, a floating hospital, supplies consist of bandages and giant boxes of surgical scrubs.

The Mercy is headed once again to areas hardest hit by the 2004 undersea earthquake in the Indian Ocean which triggered a tsunami.

Hospital corpsman Melisa Espinosa made her first trip in 2006 and came away changed forever.

"I mean, a lot of people don't have stuff that we have access to, especially medical care and the training, all kinds of things. It was a life-changing experience; I'm so happy to be here again and perhaps see some of the same people again but better," said Espinosa.

Scores of people were treated both on the ship and on shore, ranging from full operations to X-rays and CAT scans.

The Navy won't be making this trip alone. Joining the military medical staff will be more than 100 civilian doctors and nurses, officials said.

Civilian volunteers come from Project Hope and the San Diego-based International Relief Team, and will work right alongside their military counterparts.

"Some of our volunteers come from major cities, some from small towns in rural America but they all share something in common: they all want to deliver care, and when they come home they say they've experienced something they'd never be able to do here in the United States," said Rand Walton of Project Hope.

Leaving on deployment is never easy, but aboard the Mercy it's a case of being ready, willing and able.

The Mercy leaves on Thursday and will be joined at sea by other hospital ships and personnel from Canada, Japan, India, Australia and New Zealand.