Arch Island located at 1.8 km north of Sangimal, southeastern tip of Yeongdo, seems to support the pointed top reaching 141m above the sea level. Except for the south and southwest coast where Korea Maritime University is located, it is made up of steep slopes, and ships cannot approach. Arch Island is called Jo (means Morning) Island because morning begins the earliest here in Busan.

There are other explanations for the origin of the name. Cute and small things are called 'Aji'. Another theory says that as the island is small and cute, it got the name Aji and it changed to Achi later.

The other theory says that Japanese soldiers were defeated at Busanopo Naval Battle during the Japanese invasion in 1592, and it was called Wachi (meaning beat) Seom(meaning island) or Wachi do (meaning island). The name changed to Arch Island due to pronunciation change over the years.