Umi Hachimangu, like many shrines, is set within a grove of trees. The grove at Umi is called Kada's Forest, after the original name of the area, Kata. It is composed of huge, ancient Camphor trees, Kusunoki in Japanese.
The Kusunoki is the largest species of hardwood in Japan and is found in the warmer western part of the archipelago, especially Kyushu, where many shrines will have them in their grounds.
The wood contains a natural insect repellant and is used as moth balls. It is also made into incense and was used to make Buddhist statues in the early Nara Period until a switch to mostly Nutmeg and then later Cypress.
The two largest trees at Umi Hachimangu are registered as National Treasures and are reputed to be 2,000 years old. The biggest is over 18 meters tall and with a spread of similar width. The circumference around the root base is 24 meters.