Screenplay is motivated by a mermaid story in story collection “Eou yadam” by Joseon scholar Yu Mong-In. Story revolves around county magistrate Kim Dam-Ryung who released mermaids into the ocean.The mermaids were caught by fisherman.
Drama series will be the last acting role for actor Lee Min-Ho before he enters into the military for approximately 2 years. Drama series is also the first acting role for actress Gianna Jun since she gave birth to her first child.
Filming began August 19, 2016 at Goesan, North Chungcheong Province, South Korea.
Filming moves to the island of Palau in late August, 2016 and filming will also take place in Spain in September, 2016.
First script reading took place October 8, 2016 in Sangam, Seoul, South Korea. The first script reading lasted for 3 hours and covered the first 4 episodes.