Angel Eye Mountain
A limestone peak with a hole pierced clean through it near the summit, above a seasonal lake.
Updated 30 August 2026
Nui Mat Than - the mountain with a hole in the eye, usually rendered as angel eye - is a limestone peak in the Cao Bang geopark with a natural opening about fifty metres across pierced right through the rock below the summit, formed as an old cave system collapsed and the surrounding rock dissolved away. Below it is a flat grassland that floods seasonally into a shallow lake, with horses and cattle grazing on it when it is dry, and the standard photograph is the hole with the water and the animals in front. It is part of the Non Nuoc Cao Bang geopark route.
What's there
- A hole through a mountain - about fifty metres across, below the summit.
- A collapsed cave system - the process that made it.
- A seasonal lake below - flooding a grazed grassland.
- Horses and cattle on the flat - when the water is down.
When to go
September to November; the lake fills in the wet season. Half a day.
Before you go
The walk across the flat is muddy or flooded depending on season. There are no facilities. The hole is best seen from a distance and the climb to it is not a marked route. Cattle graze the ground you walk over.
Nearby
Phong Nam valley is close; Ban Gioc waterfall is north-east.
What to pack for Angel Eye Mountain
Chosen from what this place is for. Tap a kit for the full checklist.
- Broken-in walking shoes or boots - Grip and ankle support matter more than looks; never hike in brand-new boots. Find on Amazon
- Head torch + spare batteries - Hands-free light is essential; caves are truly dark. Find on Amazon
- Layers + a waterproof shell - Mountain weather turns fast; a packable rain jacket saves the day. Find on Amazon
- Grippy closed shoes - Cave floors are wet, muddy and slick with formations. Find on Amazon
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Opening times, ticket prices and seasonal closures change - check the official source before you go: official site.
