A transatlantic telegraph cable is an undersea cable running under the Atlantic Ocean used for telegraph communications. The first was laid across the floor of the Atlantic from Telegraph Field, Foilhommerum Bay, Valentia Island in western Ireland to Heart's Content in eastern Newfoundland.efore the first transatlantic cable, communications between Europe and the Americas took place only by ship. Sometimes, however, severe winter storms delayed ships for weeks. The transatlantic cable reduced communication time considerably, allowing a message and a response in the same day.