Since 1946, the US government has maintained fleets of various "mothballed" ships that can be readied and used in case of a crisis.

These boats, some of which are very old, include military ships that served in World War II, the Korean War, the Vietnam War, and Desert Storm, as well as civilian merchant ships from previous decades. The fleets sit, mostly untouched and off-limits, in the coastal waters of California, Texas, and Mississippi as well as North Carolina and New Jersey.

One of the fleets, located off the coast of San Francisco in Suisun Bay, once counted as many as 340 ships in its ranks. Today, 10 ships remain, rusting in the California sun and leaving toxic chemicals in the water. The US Maritime Administration has mandated their scrapping. By 2017 they will all be gone.

Boarding these ships is strictly prohibited to the general public — getting onto one at all is a tall task. But photographer Amy Heiden gained access to the decaying ships before some of them were scrapped, shooting on their decks and inside the vessels.