It was covered with tall trees and the swamp was a crystal-clear river.

那里覆盖着高大的树木，沼泽是一条清澈的河流。

youdao

The K18 coalbed was formed in a high position forest swamp covered by shallow water on the structure of estuary sediments and it was finally covered by estuary sediments.

K18煤层是河口湾沉积格架上形成于浅覆水高位森林沼泽之中，最终又被河口湾沉积所覆盖。

youdao

Hunters covered a million acres of swamp and sawgrass, officials said.

CNN: February 17, 2013 -- Updated 0214 GMT (1014 HKT)