A Heavy Seas Warning) is a 2005 South Korean romantic drama film directed by Jeon Yun-su.

The film starts in modern-day Korea, where Kim Su-ho (Cha Tae-hyun) returns to his hometown after ten years to attend a reunion with high school friends.

As he walks he hears a female voice in his head calling out his name.

They say that day of their reunion is the anniversary of the death of a girl named Bae Su-eun (Song Hye-kyo).

In a flashback, a younger Su-ho is rescued from drowning by a pretty girl.

His friend says she always stares at him in class, and Su-ho starts to think she might be interested in him.

Soon the captain of the judo club who had his eye on Su-eun finds Su-ho, and threatens him.

He leaves a message for Su-eun expressing his feelings, unaware that she is behind him until she replies, "Me too."

While Su-ho is visiting the hospital Su-eun expresses her wish, and he shows her two ferry tickets.

In the present, Su-ho returns to Fog Island and finds Su-eun's bag.

Her diary entry reveals that she had planted seeds on the hill during their visit.