Sea cliffs that jut out into open waters are a common sight in Japan, but in Ogasawara there's one that looks like it has been stamped with a red heart. This heart-shaped red boulder is known as Chihiroiwa or "Heart Rock". Over 200 meters off the ground, Chihiroiwa is a remarkable sight, especially when seen from the waters of Maruberi Bay. Its rusty red color is said to be the effect of rainfall washing away its surface.
Trekking tours are available to reach the rock, but you will need to be accompanied by a guide with a permit. In winter, the rock also serves as a spot where people can observe humpback whales.