Sunken heroes

The archaeological work on the shipwreck in Dandong employs China's first scientific-research vessel specially created for underwater archaeology. [Photo provided to China Daily]

"The wreck was severely damaged due to corrosion," Zhou says. "Many parts were really rusty."

Historical files show the ship was 72 meters long, but only 61meters of it remain. Its original roughly 8-meter height has diminished to 2.5 meters.

Archaeologists have tried using zinc compounds to slow the corrosion.

Another challenge is that the whole wreck was buried in sand, which had to be cleared away slowly by excavators.

How－and if－the wreck can be exhibited in the future has yet to be determined.

According to Ding Hui, a cultural official in the Liaoning provincial government, the province will seek the status as a province-level cultural heritage for the site and mark a protection zone around the wreck. But he admits there are difficulties.

"The artifacts relevant to Zhiyuan were scattered in a larger area than the ship per se," he says.