Pantano vs. ciénaga
The Spanish language, like many others, often has multiple words for similar concepts. 'Pantano' and 'ciénaga' are two such words, both broadly translated into English as 'swamp' or 'marsh'. However, subtle differences in their connotations can be highlighted through examples.
Pantano
In a general context, 'pantano' means a swamp, generally implying a wetland that is dominated by woody vegetation. It can also refer to a reservoir or manmade lake in certain contexts.
El pantano está lleno de caimanes.
(The swamp is full of alligators.)
El pueblo se construyó cerca del pantano.
(The town was built near the swamp.)
La construcción del pantano ha causado controversia.
(The construction of the reservoir has caused controversy.)
Ciénaga
'Ciénaga' also means 'swamp', but it often denotes a marshy area where water stagnates. It refers to more of a marshland that is frequently or continually inundated with water and typically characterized by emergent soft-stemmed vegetation.
Las ciénagas son hogar para muchas especies de pájaros.
(Marshes are home to many species of birds.)
La ciénaga estaba llena de lirios de agua.
(The marsh was full of water lilies.)
La ciudad costera está rodeada de ciénagas.
(The coastal city is surrounded by marshes.)
Summary
'Pantano' and 'ciénaga' are different types of wetlands with subtle distinctions. The primary difference lies in their usage: while 'pantano' generally refers to swamps with woody vegetation or artificially created reservoirs, 'ciénaga' commonly designates naturally occurring marshlands where the water stagnates and supports emergent soft-stemmed vegetation.