Floating in the Kitan Strait just off the coast of Wakayama, Tomogashima is a cluster of uninhabited islands that feels completely detached from modern Japan. Once a highly restricted military fortress from the Meiji era through World War II, the islands were ultimately abandoned and reclaimed by nature. Today, Tomogashima is famous nationwide for its uncanny resemblance to the world of Studio Ghibli's Castle in the Sky (Laputa). Overgrown red-brick gun batteries, dark subterranean tunnels, and vibrant coastal views create an atmosphere of eerie isolation and breathtaking beauty. In this comprehensive guide, I break down everything you need to know about hiking these historic ruins, navigating the crucial ferry logistics, and the best driving and train routes to get there from the Kansai region.

Tomogashima is essentially an open-air museum crossed with a rugged nature hike. The island you will actually be visiting is Okinoshima (the main island of the cluster), and the hiking trails connect several different abandoned military sites.

• The 3rd Gun Battery Ruins (第3砲台跡): The undisputed highlight of the island and the main reason most people visit. This sprawling, subterranean complex of red-brick ammunition depots and artillery emplacements is heavily overgrown with moss and ferns, creating the iconic, magical Laputa atmosphere.

• Underground Tunnels: Unlike many historical ruins in Japan, you are actually allowed to walk inside the dark, winding tunnels of the fortress. It is incredibly atmospheric, but pitch-black in some sections—bringing a smartphone flashlight or a small torch is highly recommended!

• Tomogashima Lighthouse & Coastal Trails: Built in 1872 by a British engineer, this white western-style lighthouse is still operational today. The trails leading to it run right along the cliffs, offering spectacular, panoramic views of the sea and Awaji Island in the distance.

• The Island Wildlife: As you hike, keep an eye out for the local wildlife. The island is populated by Taiwan squirrels and wild deer that occasionally cross the paths, adding to the untouched, wild feel of the destination.