marsh an area of low flat ground that is always wet and soft, that often has grasses or reedsgrowing in it but no trees
The low hills you can see are like islands surrounded by the marsh.
Miles of salt marsh (=which has salt water under it because it is near the sea) stretched before us, reaching to the shores of the River Severn.
Hackney Marshes
the rustling of the marsh grass
swampland that is always very wet or covered with a layer of water, that often has trees growing in it – used especially about areas in hotcountries
the swamps of Florida
Less than 200 years ago, the city was a swamp, infested by mosquitoes.
bog an area of low wet muddy ground, sometimes with bushes or grasses growing in it
His foot started slowly sinking into the bog.
The destruction of peat bogs is contributing to global warming, according to a report commissioned by Friends of the Earth.
wetland an area of land that is partly covered with water, and that has grasses and other plants growing in it – often used about areas that are important to birds or wildlife
The ecosystem of the world 's largest wetland, the Pantanal in southwest Brazil, is being threatened by tourists.
wetland birds
fen a large area of low flat wet land – used especially about the area of this type of land in eastern England in Cambridgeshire and Lincolnshire, which is known as the Fens
He grew up in the Fens
Intensive cultivation and continued drainage of the Fens further accelerates the degradation of the land.
mire literary an area of wet muddy ground, which people and vehicles etc get stuck in