The Meridian trench, located on the first Death Star, was a trench encompassing a portion of that battlestation. It housed the station's greatest weakness: a thermal exhaust port situated near the station's north pole, which is why it was also known as the Polar Trench. If weaponry was fired into it, the exhaust port would cause the Death Star to under go a critical chain reaction. The Alliance to Restore the Republic utilized this trench to destroy the Death Star before it blew up their base on Yavin 4.