USS Arizona faces another foe at Pearl Harbor: corrosion.(Knight Ridder Newspapers)

She remains one of America's most hallowed places, still holding the bodies of more than 900 sailors and Marines who died in a rush of explosions on a lush tropical morning 60 years ago, still resting in Pearl Harbor's muck.

But for how long, nobody knows.

Because the unsentimental sea is having its methodical way with the USS Arizona, slowly corroding the old battleship that sank during the Japanese attack.

At some point, federal officials will have to decide whether to fight the sea and preserve the ship as much as possible, or let nature take its course and allow the ship to collapse and disappear into the tides.

Complicating their decision is the presence on board of an estimated 500,000 to 750,000 gallons of heavy fuel oil, which could be released into Pearl Harbor should the ship collapse.

Those studying the ship can't say yet how long it will last intact without intervention.

"The collapse of this thing is not imminent," said Donald Johnson, a retired professor of mechanical engineering at the University of Nebraska who is one of the researchers. "It's not something we're looking at in the next few years. ... It will eventually corrode and collapse."