thick as pea soup
(as) thick as pea soup
Extremely thick or heavy. Usually said of conditions in the air, especially fog. We were just readying our boat when fog, thick as pea soup, rolled in and covered the entire harbor. The humidity in the air felt as thick as pea soup, and it caught in our throats as we trekked through the jungle.
Farlex Dictionary of Idioms. © 2015 Farlex, Inc, all rights reserved.
*thick as pea soup
[of fog] very thick. (*Also: as ~.) This fog is as thick as pea soup. You can't see ten feet in front of you.
McGraw-Hill Dictionary of American Idioms and Phrasal Verbs. © 2002 by The McGraw-Hill Companies, Inc.