“Across the pond” is an idiom that typically refers to the United Kingdom and the United States being on opposite sides of the Atlantic Ocean. This expression is an understatement, often used as a humorous reference to the approximately 3,500 miles (5,600 km) between the coasts of each country.
The United Kingdom is composed of several islands off the northwest coast of Europe. Four separate countries, England, Northern Ireland, Scotland, and Wales, belong to the United Kingdom. London is the capital city, as well as the largest city and a hub for transatlantic air travel.
On the opposite side of the Atlantic Ocean lies the United States. Both the United States and the United Kingdom speak English as the official language. The U.S. has two main transatlantic hubs, one in New York City, New York, and the other in Detroit, Michigan, as well as several smaller hubs across the eastern half of the country.
Although “across the pond” is primarily a British idiom used in reference to the United Kingdom and the United States, the phrase can also refer to Canada. Canada has transatlantic hubs in both Montreal and Toronto. On the eastern side of the Atlantic, the idiom occasionally refers to Europe in general. This usage is far less common.
The Atlantic Ocean is the only ocean ever referred to in the saying "across the pond". South America and Africa are never referred to in this idiom, even though they are across the Atlantic from each other. This is due to the fact that the saying is an English idiom, which is spoken widely in the United Kingdom, the United States, and Canada, but rarely in the countries of South America and only in some areas of Africa.
As a literary device, “across the pond” is an understatement. Unlike hyperboles, understatements treat something as less than it is. A common understatement is calling a bad injury “just a scratch". Speaking of the Atlantic Ocean, a 41,100,000 square mile (106,400,000 sq. km.) body of water, as a pond is a humorous understatement.
Not only is the idiom an understatement, it can also be seen as irony. An ironic statement is one that means the opposite of what it literally says. When someone says they are traveling “across the pond,” they state it as if they are crossing a small body of water, when in reality they are crossing the second largest body of water in the world.