First in a series of stories about weapons disposed at sea off Hawaii's shores.

There are thousands of tons of chemical weapons lying just miles off Hawaii's coast.

That's according to Army documents detailing ocean dumping going back 60 years.

The Army's own catalog of munition dumping shows tens of thousands of mustard-gas bombs, and other deadly ordnance dating back to World War II.

More than 30,000 mortar shells filled with mustard agent were dumped at sea somewhere beyond the Waianae coast 60 years ago -- that, and a lot more.

A military inventory of offshore chemical weapon dumping reveals tons of hazardous waste as close as five miles off the coast at several points around the islands. That's thousands of feet deep, yet ordnance litter is frequently found offshore.

"This is the pin from a grenade, and there are areas in about 80 feet of water off Waianae and Maili where this stuff is literally strewn across the bottom," says William Aila, Waianae harbormaster.

Whether items close to shore are the same as those dumped munitions is unclear. According to Army documents, chemical weapons were loaded at Waianae and taken to sea for disposal. Congress banned the practice in 1970.

Army research details items taken out of Waianae alone:

• 1,000-pound hydrogen cyanide and cyanogen chloride bombs
• nearly 15,000 mustard bombs
• more than 30,000 4-inch mortar mustard shells
• more than 1,200 1-ton containers of both mustard agent and a blistering chemical called lewisite.

The Army says a dump of hydrogen cyanide off Pearl Harbor was probably to blame for an injury to a crewman after a boat dredged it up in the 1970s.

It's speculated dumped chemical agents may be to blame for injuries to marine wildlife in other parts of the country.

"If any one of those canisters should start leaking -- because of the upwelling, and because of our location, and because of the way that the tradewinds work," says Aila, "about 80 percent of the time the contents of that is going to be brought toward shore."

The Army Chemical Weapons Material Agency in Washington tells KHON2 seepage from eroded or damaged shells would likely neutralize before reaching the surface and washing ashore.

The state was unaware of the scope of chemical weapons offshore until we questioned them for our story.

Now they say they'll look into it but think the military would be responsible for cleanup.