Pea soup fog is a type of fog that is very thick, heavy and usually restricts visibility to just a few meters. There are a number of synonyms for this type of fog that are commonly used, all describing the same weather phenomenon but using different terms. These synonyms include thick fog, dense fog, London fog, sea fog, ground fog, and mist. Each of these terms is used interchangeably to describe a very concentrated fog that is difficult to see through, causing potential hazards for drivers, pilots, and boaters alike. Regardless of the term used, any type of fog can make visibility difficult and potentially dangerous in certain situations.