The island is covered by a forest. The only known building on the island is a high tower with trees on a roof.
The World Government uses Guanhao as a training camp for future Cipher Pol generations. Rob Lucci and other CP9 members had trained on the island until they became strong enough to become full-fledged agents.
CP9's Independent Report
- The tower on Guanhao bears a resemblance to the East Tower on Jiang Xin Yu in Wenzhou.
- The island may be named after a Chinese fan who asked Oda about the tower mentioned above. The fan's name is Wu Guanhao (吳冠昊).
- Vivre Card - One Piece Visual Dictionary, Guanhao's name is revealed.
- One Piece Manga — Vol. 53 Chapter 518, cover story: CP9's Independent Report Vol. 25.
- One Piece Manga — Vol. 53 Chapter 521, cover story: CP9's Independent Report Vol. 27.
- One Piece Manga — Vol. 54 Chapter 525, cover story: CP9's Independent Report Vol. 31.
- SBS One Piece Manga — Vol. 80, A fan asks Oda about an inspiration for the tower on Guanhao.