According to the survey conducted by The Geographical Survey Institute of Japan, the total area of wetland in Japan is 820.97 km2, and 708.67 km2 of those are located at Hokkaido. Those figures were 2110.62 km2 for total wetland and 1771.99 km2 of those for Hokkaido about 100 years ago.
These figures show that Hokkaido has large part of wetand in Japan all the time from the past to present.
Kushiro wetland are known as the largest wetland in Japan, and the area is 203.66 km2. Howeverm it was 251.46 km2 a century ago, so about 19% of the area has been disappered.
Wetland in general looks like grassland and streams, but those are not actually grassland but bottomless swamp sometimes. In fact, it is known that Kushiro wetland was called as "Horse Killer" by the groundbreakers.
From the universe, on the other hand, this wetland can not be seen as bottomless swamp, but complex combination of water, ground, and vegetation, and the combination would be dramatically changed over the seasons.
Not only Kushiro wetland, but also wetlands in general have so many kind of countenance dependent on where, when, and what to see.
LaｎdsatTM （June 5th 2001） Yellow line indicates Kushiro Wetland National Park
Wooden parthways are available for sightseeing purposes at Kushiro wetland.