When South Korean archaeologists announced on November 10 that they had recovered a 15th-century tax ship from the seabed off the western coast of Taean, another discovery from the same waters captured equally stunning attention. Divers had located two tightly stacked bundles of celadon pottery from the Goryeo Kingdom (935-1392), containing 87 pieces in total that are believed to date from around 1150 to 1175. After basic cleaning, these nearly 900-year-old bowls and cups were presented to the press, arranged neatly on black fabric and acrylic stands with surfaces gleaming brilliantly under the lights.
The most remarkable aspect of these ancient ceramics is not just their mirror-like shine, but their complete preservation. "In this case, we recovered all 87 celadon pieces intact," said Hong Gwang-hui, a researcher in the National Research Institute of Maritime Cultural Heritage's Underwater Excavation Division. "The preservation rate was effectively 100 percent." The ceramics were discovered stacked in nested bundles, likely in the exact same configuration they had been in when originally loaded onto the ship centuries ago.
This strategic packing method proved crucial to their survival over the centuries. "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 condition wasn't limited to just a select few pieces either – because all 87 items were found whole, there was no need to handpick only the best-looking specimens for press photographs.
The secret to this extraordinary preservation lies beneath Korea's UNESCO-listed tidal flats along the west coast. Taean sits in an area lined with expansive mudflats rich in fine, clay-heavy sediment that creates one of the world's most effective natural preservation environments for underwater cultural heritage. "Our west coast tidal flats are dominated by dense clayey deposits," explained Park Ye-ri, also a researcher in the institute's Underwater Excavation Division. "Once a wreck settles and is buried, the artifacts are essentially sealed under a thick mud layer."
This natural seal creates two critical preservation conditions. First, it establishes an anaerobic, low-oxygen environment that sharply reduces microbial activity, limiting damage to organic materials like wooden hull planks, cargo tags, and even seeds. Second, the cohesive clay completely immobilizes artifacts, protecting them from movement and physical stress that would normally cause deterioration.
"The biggest threats to underwater ceramics are not corrosion but friction, impact and rolling," Park noted. "Once a bowl sinks into cohesive mud, it doesn't move. It doesn't scrape against rocks. That's why it survives." This protective environment is so effective that the clay-rich mud sealed away the 12th-century shipwreck so perfectly that its celadon cargo now gleams as if it just emerged from a kiln.
The preservation quality varies dramatically depending on the seabed environment, as evidenced by contrasting discoveries in other Korean waters. The same research institute has spent years excavating a Chinese Southern Song era (1127-1279) trade ship off Sinchang-ri waters on Jeju Island, where conditions tell a completely different story. "There the seabed is mostly rock and sand," Park said. "The area is exposed to strong wave energy, and there is a higher possibility of damage from microorganisms and marine life."
Ceramics recovered from the Jeju site show extensive breakage and abrasion, with many pieces heavily encrusted or damaged, and a significant portion surviving only as fragments scattered across the rocky seabed. The contrast is stark – while Taean's protected mudflats preserve entire stacks of perfect bowls, Jeju's exposed, high-energy environment offers little protection for underwater artifacts.
This preservation advantage extends throughout Korea's western and southwestern coastal regions. Moving away from the clay-rich flats of Taean, Shinan, or Wando toward areas like Goheung, Yeosu, or Geoje on the southern coast, the ratio of sand and rock increases while protective mud decreases. The further a shipwreck lies from those thick tidal flats, the more punishment its cargo typically suffers from the marine environment.
While Korea's West Sea produces remarkable preservation results, researchers caution against assuming it's uniquely superior worldwide. "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 geological conditions exist along the Chinese side of the Yellow Sea, which shares continuity with Korea's west coast, and Chinese shipwrecks like the Nanhai One, also buried in dense seabed sediment, show comparable preservation quality.
What distinguishes the Taean area is a unique combination of favorable factors concentrated in one location. The shallow depth, extensive mudflats, and centuries of dense maritime traffic along state and commercial sea routes have produced an unusually concentrated cluster of historic wreck sites, making it a hotspot for underwater archaeological discoveries.
For archaeologists, while the public finds these pristine celadon bundles attention-grabbing because they look almost unreal, they represent part of a longer, methodical research process. "Simply finding a stack of celadon is not, by itself, extraordinary," Hong explained. "We already have many examples of large ceramic cargoes from Korean waters." The real archaeological significance will depend on what future excavation work reveals about the ship that carried these precious items.
Divers have already located additional artifacts near the pottery, including a wooden anchor, anchor stones, rice grains, and timber fragments. The research institute plans further excavation to confirm whether this newly discovered Goryeo Kingdom wreck, unofficially labeled Mado 5, lies buried in the protective mud alongside the previously identified vessels Mado 1 through 4.
"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." The discovery adds another chapter to the rich maritime history preserved beneath Korea's western tidal flats, where the unique seabed conditions continue to yield treasures that look as fresh as the day they were crafted nearly nine centuries ago.
