Cambodia–Laos border
A border drawn inside French Indochina, running from the Annamite Chain across the Mekong valley to the Dangrek escarpment. Where it crosses the Mekong, a deep pool on the line was home to a small group of Irrawaddy river dolphins; the last of them died in 2022, and with him the species vanished from Laos.
Written from cited sourcesLast checked 29 September 2026Suggest a correction
See it on the globe:Cambodia →Laos →
An Indochinese line
The line comes from France’s protection of Cambodia and Laos and from the internal decisions of French Indochina, backed by treaties with Siam between 1867 and 1904. From the Vietnamese tripoint it runs west along the plateaus of the Annamite Chain, down into the middle Mekong valley by the Se Kong, crosses the river, and follows a broad plain to the sandstone escarpment of the Dangrek at the Thai tripoint. For most of its 336 miles it follows water divides.[1]
The last dolphin
In the Mekong, the Chheu Teal pool spans the border. In 1993 it held 17 Irrawaddy river dolphins; by 2018 only three were left, and by 2021 a single male, known as ID#35. In February 2022 he died after being caught in illegal fishing gear, and with him the species was extinct in Laos. Experts blamed gill nets and illegal fishing, overfishing, genetic isolation and upstream dams. About 89 dolphins remained in the Mekong, all in Cambodia.[2]
“the last Irrawaddy river dolphin in a transboundary pool between Cambodia and Laos became entangled in fishing gear and died”[2]
Timeline
More borders
Sources
- [1]International Boundary Study No. 32: Cambodia – Laos Boundary · US Department of State, Office of the Geographer · 12 June 1964
- [2]Death of last river dolphin in Laos rings alarm bells for Mekong population · Mongabay (Carolyn Cowan) · 14 April 2022
Map geometry from Natural Earth via world-atlas. See credits.