Gensei Marsh
Gensei Marsh is located west of the jigoku hot springs. Designated a natural monument in 1928, the marsh is one of Japan’s rarest landscapes, a biodiversity hot spot, and an excellent example of ecological succession.
Scientific analysis has shown that Gensei Marsh used to resemble the barren landscape of Unzen’s jigoku hot springs. However, over thousands of years the hot springs have slowly shifted west. The area under the marsh has cooled, causing a vibrant ecosystem to emerge in a place where 1,500 years ago almost nothing could grow.
First, as conditions improved, sphagnum (peat moss) quickly covered the whole area. Today, the marsh is home to a wide variety of plants, from flowering Japanese azaleas to insect-eating sundews and rabbit-ear irises. Unfortunately, the water level has dropped, possibly due to climate change, so a century from now the marsh may look completely different.