Uyuni Salt Flat, Bolivia

“The Uyuni Salt Flat, situated in the lowest part of the central high-plateau (12000 ft/3656 mts above sea level). In the summer the Uyuni Salt marsh is a huge lakeabout half the size of Belgium with a depth of 60 to 80 cm.”
http://www.condorjourneys-adventures.com/bolivia_circ1.asp

World’s Largest Swamp

“As Sudd, the world’s largest swamp, provides a formidable expanse of lakes, lagoons, and aquatic plants, whose area in high flood waters exceeds 30,000 square kilometers, or approximately the size of Belgium.”
http://www.photius.com/countries/sudan/geography/sudan_geography_geographical_regions.html

Lake Saimaa drainage region

“Saimaa is a labyrinthine watercourse whose waters flow slowly from north to south and finally through its outflow channel, the Vuoksi, southeast over the Russian border into Ladoga, Europe’s largest lake. The Saimaa drainage region covers most of the southern part of eastern Finland, a region about the size of Belgium.”
http://virtual.finland.fi/netcomm/news/showarticle.asp?intNWSAID=25710

Simpson Desert, Australia

“The Simpson Desert is six times the size of Belgium.”
http://www.postcards.sa.com.au/features/simpson.html

Lake Baikal

“Lake Baikal, near Irkutsk, is one of the world’s natural wonders. It’s 636km long, it covers 31,500sq km (roughly the size of Belgium) and it is one of the Earth’s geographical features visible from space.”
http://www.francismckee.com/baikal.htm

Wetland areas in Sweden

“It is estimated that wetland areas in Sweden total some 93,000 km2 (9,3 million hectares), which means that more than 20% of the country’s total land area is classed as wetland. For a rough European comparison the total area of Belgium is 30,518 km2.“
http://www.internat.naturvardsverket.se/index.php3?main=/documents/nature/nacatego/wetlands/wetlands.htm