Otters, which are at risk of extinction in South Korea, have been found in the Han River in Seoul.
The Han River Basin Environmental Office said Wednesday that an unmanned camera captured footage of a mother otter and three cubs.
Otters had been commonly found in rivers and streams around the nation, but their numbers dwindled drastically due to water pollution and excessive hunting.
It has been believed that otters disappeared from the downstream area of the Han River after the construction of the Paldang Dam in 1973 severed the upstream and downstream ecosystems.
After an otter sighting was reported at a Han River tributary in March of last year, the environmental office conducted a detailed study of the otters' ecosystem along the river and placed ten unmanned cameras to observe the animals.