November 28, 2025
SEOUL – When South Korean archaeologists announced on Nov. 10 that they had raised a 15th-century tax ship from the seabed off the western coast of Taean, photographs of another find from the same waters also drew major attention.
Next to the Joseon-era (1392-1910) vessel known as Mado 4, divers had located two tightly stacked bundles of celadon from the Goryeo Kingdom (935-1392), 87 pieces in total, believed to date from around 1150 to 1175. After basic cleaning, the bowls and cups were presented to the press, neatly arranged on black fabric and acrylic stands, surfaces gleaming under the lights.
But if these were really nearly 900 years old, how could they look as if they had just come out of a furnace?
Researchers at the National Research Institute of Maritime Cultural Heritage told The Korea Herald the public reaction is understandable, but explained the answer is less mysterious than it seems.
How can pottery that old come out of the sea completely unbroken?
The most surprising fact about the Taean find is not only the shine, but the completeness.
“In this case, we recovered all 87 celadon pieces intact,” said Hong Gwang-hui, a researcher in NRIMCH’s Underwater Excavation Division.
“The preservation rate was effectively 100 percent.”
The ceramics were found stacked in nested bundles, likely in the same configuration they had been in when first loaded onto a ship. That packing style turns out to be more than just space-saving.
“When ceramics are nested, the inner bowls are naturally shielded from external impact,” Hong explained.
“Even if cracks form, they’re usually minor and restorable.”
The pristine appearance was not limited to a curated few. “Because they were all whole, there was no need to handpick the best-looking ones for press photos,” Hong added.
What kind of seabed were these bowls lying in?
That near-perfect condition is as much a product of the seabed as the pottery itself.
Taean sits along Korea’s west coast, an area lined with expansive tidal mudflats rich in fine, clay-heavy sediment. Known for their ecological value and listed as a UNESCO World Heritage, these flats also happen to create one of the best natural preservation environments for underwater cultural heritage.
“Our west coast tidal flats are dominated by dense clayey deposits,” said Park Ye-ri, also a researcher in NRIMCH’s Underwater Excavation Division.
“Once a wreck settles and is buried, the artifacts are essentially sealed under a thick mud layer.”
That seal has two key effects: First, it creates an anaerobic (low-oxygen) environment, which sharply reduces microbial activity. That limits damage to organic materials like wooden hull planks, cargo tags, or even seeds. Second, the cohesive clay immobilizes artifacts, protecting them from movement and physical stress.
“The biggest threats to underwater ceramics are not corrosion but friction, impact and rolling,” Park explained.
“Once a bowl sinks into cohesive mud, it doesn’t move. It doesn’t scrape against rocks. That’s why it survives.”
Do shipwrecks in other Korean waters also look like this?
Move away from those mudflats, and the picture changes.
For example, the same institute has spent years excavating a Chinese Southern Song era (1127-1279) trade ship off Sinchang-ri waters on Jeju Island, a site researcher Park points to as a contrasting case.
“There the seabed is mostly rock and sand,” she said. “The area is exposed to strong wave energy, and there is a higher possibility of damage from microorganisms and marine life.”
Ceramics from Sinchang-ri show far more breakage and abrasion. Many pieces are heavily encrusted or spalled, and a significant portion survives only as fragments.
Move away from the clay-rich flats of Taean, Shinan or Wando on the western and southwestern coast, toward Goheung, Yeosu or Geoje on the southern coast, Park noted, and the ratio of sand and rock rises while the protective mud decreases. The further a wreck lies from those thick tidal flats, the more punishment its cargo is likely to suffer.
Is Korea’s western coast unique in preserving shipwreck ceramics?
The photographs from Taean invite a tempting conclusion that Korea’s West Sea must be uniquely good at preserving underwater treasures. Park is much more cautious.
“From a research perspective, the preservation of these pieces is not exclusively better than previous finds from the Mado area, or anywhere else in the world,” Hong said of the celadon bundles. “It is very good, but it is consistent with what we expect from that environment.”
Similar environments exist elsewhere in East Asia, notably along the Chinese side of the Yellow Sea, which shares geological continuity with Korea’s west coast. For example, Chinese shipwrecks such as the Nanhai One, also buried in dense seabed sediment, show comparable preservation, Hong pointed out.
What distinguishes Taean, in the view of the Korean researchers, is a combination of factors in one place. Shallow depth, extensive mudflats and centuries of dense traffic along state and commercial sea routes have produced an unusually concentrated cluster of wreck sites.
How big a discovery is this celadon bundle to archaeologists?
For the public, the Taean celadon bundles are attention-grabbing because they look almost unreal. For the archaeologists, they are part of a longer, patient process.
“Simply finding a stack of celadon is not, by itself, extraordinary,” Hong said. “We already have many examples of large ceramic cargoes from Korean waters.”
The real significance will depend on what future work reveals about the ship that carried them. Divers have already located a wooden anchor, anchor stones, rice grains, timber fragments and other items near the pottery. The institute plans further excavation to confirm whether the new Goryeo Kingdom wreck, unofficially labelled “Mado 5,” lies buried in the mud.
“If wooden tags or bamboo tallies are found inside a hull, they can tell us where the ceramics were made and who they were being sent to,” Hong said. “Providing that kind of context is what archaeology aims to do. We are not just raising artifacts, we are reconstructing the connections around them.”