Hyotannuma
At one time this swamp was shaped like a gourd (hyotan), hence its name. The swamp is shrinking as it transitions to wetland and forest, however, so the shape is no longer discernable. The dead leaves and other detritus that have settled on the bottom can be seen in the clear, shallow waters of the swamp. As the sediment decomposes and the water level becomes shallower, plants like sedge and bulrush thrive (visible on the right side of the swamp). Eventually reeds (tall grasses visible on the far side of the swamp) will grow, turning the swamp into marshland. Over a long period of time, the marsh will convert to land, and this will become home to a forest of Japanese horse chestnut and beech trees.