At 84 years old, Donald Stratton hasn't forgotten how to be a proper sailor.
As he gingerly walks up the ramp into the elegant white memorial that straddles the sunken battleship USS Arizona in Pearl Harbor, Hawaii, he pauses to salute.
"You always salute the officer of the deck, and ask permission to come aboard, sir," he said.
"It brings back a lot of memories," Stratton said, following a short boat ride that brought him out to the memorial. "And not a lot of good ones, either."
Today is the 65th anniversary of the Japanese surprise attack on Pearl Harbor that killed 2,395 Americans and plunged the United States into World War II. About half of the dead were Stratton's shipmates on the Arizona, which exploded and eventually sank after an armor-piercing bomb ignited 1 million pounds of explosives below deck. Stratton suffered burns on more than 60 percent of his body and was just barely able to escape by climbing a rope to a nearby ship.
Painful Reality of Time
Every five years, thousands of Pearl Harbor survivors like Stratton have always come back to commemorate Dec. 7. But as time passes, many are finding it harder to come back.
This year, he brought his wife, Velma, son Randy and granddaughter Nikki to the USS Arizona Memorial to share in the painful memories of that day. Randy's wife, Kathy, and family friend Wayne Mercer also came along.
As they toured the memorial a few days ago, Stratton fondly talked about the Arizona as if he could still see it docked in the harbor.
"It was 605 feet long," he said, pointing to a diagram of the battleship.
Stratton's loved ones stood behind him. Several were in tears.
Stratton knows he is fortunate -- he is still in good enough health to make the five-hour flight to Hawaii from his California home. For many veterans, however, the realities of old age and declining health, combined with the rigors of travel, have made them realize this is likely the last time they will gather in this hallowed place.
"As an organization, we won't be back here again," says Mal Middlesworth, president of the Pearl Harbor Survivors Association. "So many of our friends can't make it. A lot of them are in wheelchairs and walkers. They don't drive at night. It's their health, basically."
More Extended Family and Friends in Attendance
Middlesworth says about 400 Pearl Harbor veterans are attending this year's reunion along with about 2,000 family and friends.
Those numbers are a sign to organizers that the 65th anniversary has prompted many vets to bring along extended family and friends to share often painful war experiences.
Clair "C.J." Fox was onboard the USS New Orleans 65 years ago and had a front row seat for the attack. He's attended reunions before, but always alone. This year, he arrived in Hawaii with eight people in tow, including his two daughters, grandchildren, and family friends.
"Any father likes to pass on part of his life to his children and let them know how things were in those days," the 89-year-old said. "Although I'm still pretty healthy in body and mind, I know it won't last forever."
His daughters also sense the clock is ticking.
"Everyone is getting older and we just want to make sure he gets a chance to see his friends and shipmates," said Suzanne Wojinsky. "We don't know how many will be around for the next time."
Middlesworth says many vets have never shared their experiences with family.
"Most WWII vets didn't talk about their military careers while they were raising a family and paying off the mortgage and getting jobs," said Middlesworth. "And now the grandchildren are involved."
Living Historical Resources -- and 'Old Friends' -- Vanishing
There are approximately 3.2 million WWII veterans still alive, according to the U.S. Department of Veterans Affairs. The department estimates that on average, nearly a thousand of those veterans are dying every day.
For Pearl Harbor historians like Daniel Martinez, the National Park Service historian at the USS Arizona Memorial, a living historical resource is disappearing before our very eyes.
"It's sad because we've come to know them and we've come to look forward to seeing them," Martinez said. "They're old friends."
The USS Arizona Memorial is a place where Pearl Harbor survivors still volunteer and often get requests for autographs from the 1.5 million visitors who come every year.
At his age, Stratton knows this could be his last visit to the site where so many shipmates are still entombed underwater. But, he says, don't count him out yet.
"If the good Lord keeps me around another five years," he said, "I'll probably be back."
ABC News' Derick Yanehiro contributed to this report.