Traditional tide‑tracking system becomes Korea's Intangible Cultural Heritage

The area where the Imjin River and the Han River converge in Gimpo, Gyeonggi Province, which served as the reference point for tidal records during the Joseon Dynasty. Courtesy of Korea Heritage Service

Korea’s centuries-old knowledge of “multtae,” the traditional system for calculating tidal movements, has been officially designated as a National Intangible Cultural Heritage, the Korea Heritage Service (KHS) announced Wednesday.

Multtae, literally meaning “tide time” in Korean, refers to the collective knowledge and system used to predict the rise and fall of ocean tides — a vital practice that for centuries has guided coastal life across the Korean Peninsula.

It serves both as a calendar of tidal cycles and as a practical science enabling people to anticipate the timing of high and low tides.

In Korea, the west coast has a higher tidal range, with up to nine meters in area near Incheon, while the east coast sees the tidal range lower than one meter.

The KHS said multtae is a “community transmission” heritage item, without an individual or group deserving recognition, for the knowledge has long been shared and practiced collectively among coastal residents.

Historical records trace the use of multtae back to the 12th century. Poet Yi Kyu-bo is believed to have written a poem inspired by the tidal time. The term “multtae” was mentioned in chronicles such as the “Goryeosa” (History of Goryeo) and the “Annals of King Taejong” of the Joseon Dynasty (1392-1910). By the late Joseon period, tidal data were often compiled into 15-day tables for broader use.

A tidal chart drawn by a fisherman on Seonjae Island in Incheon to track the tide patterns / Courtesy of Korea Heritage Service

For island and coastal communities, multtae has been indispensable to daily life and livelihood. It guided traditional fishing, salt farming, land reclamation and even determined the timing of boat departures in certain regions. The knowledge also facilitated the construction and safe use of “nodu,” stone walkways that connected tidal flats between islands.

Today, multtae continues to hold contemporary value, finding new life in calendars and smartphone apps that track tidal changes.

“We plan to actively support academic research and transmission programs related to multtae so that its value as a National Intangible Cultural Heritage can be shared widely with the public,” the KHS said in a statement. “We will continue to expand the designation of new intangible heritage items through proactive administration and strive to ensure that Korea’s traditional culture is passed down to future generations.”