Tacna is a census-designated place (CDP) in Yuma County, Arizona, United States. The population was 555 at the 2000 census. It is part of the Yuma Metropolitan Statistical Area.
Tacna is located at 32°41′45″N 113°57′47″W / 32.69583°N 113.96306°W / 32.69583; -113.96306 (32.695927, -113.962997).
According to the United States Census Bureau, the CDP has a total area of 1.9 square miles (4.9 km²), all of it land.