Niji-no-Matsubara, stretching along the Karatsu Bay coastline, is designated as a national scenic beauty spot and is considered one of the three greatest pine forests of Japan together with Miho-no-Matsubara and Ama-no-Hashidate. Niji-no-Matsubara is approximately 5 km in length, 1 km wide and made up of around 1 million Japanese Black Pine trees.