El Salvador–Guatemala border

The El Salvador–Guatemala border is a 203 km (126 mi) international boundary in the northeast–southwest direction, northwest of El Salvador, and separating the country from the territory of Guatemala. From north to south, it starts in the triple border of the two countries with Honduras, near the peak Monte Cristo in Volcanoes National Park, extending to the southwest by the Pacific Ocean coast, following the final stage the Rio Paz.

Source: Wikipedia — El Salvador–Guatemala border (CC BY-SA 4.0)