Belgium Trougnouf (Benoit Brummer) · CC BY 4.0
The descent
The entrance, at 180 m.
The real relief above Neptune Caves, measured on the Copernicus model every 30 m, and the cave going down at the same vertical scale.
The depth is the one published by those who explored it; the shape of the galleries is a sketch, not a survey. No depth has been published for this cave yet.
180m
Entrance altitude
from the 30 m relief model
10°C
Inside, all year
the yearly average outside, at the entrance
90m
Rock above
the highest point within 1.5 km
Inside and outside
10 °C inside, all year.
Deep inside, a cave keeps the average temperature of the year outside: about 10 °C here, in January and in August. In July the afternoon reaches 23 °C at the entrance, 13 °C warmer than inside: take a jacket. The wettest months are in December: water rises fast underground, so never go in without a guide after heavy rain.
- 4°-1°Jan
- 5°-1°Feb
- 10°1°Mar
- 14°4°Apr
- 18°8°May
- 21°11°Jun
- 23°13°Jul
- 22°13°Aug
- 19°9°Sep
- 14°6°Oct
- 9°3°Nov
- 5°0°Dec
Outside: afternoon and night averages for 1991–2020 (NASA POWER) brought to the altitude of the entrance. Inside: the yearly average, which deep parts of a cave keep. Near the entrance it follows the weather a little.
Show caves near Couvin, Belgium
Neptune Caves is a show cave in Belgium. The entrance is at 180 m. It has an underground river and stalactites and stalagmites. It is open to visitors.
Getting there.
- Show cave: open to visitorsticket required
- Frasnesnearest town · 1.6 km in a straight line
- Parking 90 m awaynearest car park in OpenStreetMap, straight line
- Tienne du Lionnearest viewpoint · 0.6 km from the entrance
- Brussels South Charleroi Airport (CRL)nearest airport with scheduled flights · 44 km in a straight lineCar hire at CRL airport (Charleroi)Discover Cars · sponsored link↗
Plan the visit
Guided tours, a bed nearby, a car.
Some links above are affiliate links: if you book through them we may earn a commission, at no extra cost to you. It never changes what the data on this page says.
The water
The L'Eau Noire runs highest from November to March.
The L'Eau Noire carries about 2.3 m³/s on average here. It runs highest from November to March.
- 3.7 m³/sJan
- 3.5 m³/sFeb
- 3.5 m³/sMar
- 2.2 m³/sApr
- 1.6 m³/sMay
- 1.1 m³/sJun
- 1.0 m³/sJul
- 1.3 m³/sAug
- 0.8 m³/sSep
- 1.5 m³/sOct
- 2.6 m³/sNov
- 3.5 m³/sDec
From about 0.84 m³/s in the lowest month to 3.7 m³/s in the highest. Its basin above this point covers 222 km².
The Eau Noire from source to mouth on Riveryas — coming soon
Estimate: long-term flow from the HydroATLAS model (WaterGAP, 1971–2000) shaped by the monthly rain, snow and temperature of the area (NASA POWER). Dams change it. Not a forecast.
From above.
The ground above the cave, with the relief shaded, the line of the section and what people have mapped around the entrance.
N
1.5 km
Sentinel-2 cloudless 2016 (EOX, CC BY 4.0), 6.0 × 6.0 km, north up. The line is the section above. Points © OpenStreetMap contributors.
Around the entrance.
- 8other cave entrances within 3 kmGrottes de Neptune, Grotte du Pont d'Avignon2, Grotte du Pont d'Avignon and 5 more
- 1springs within 2 kmSource
- 3viewpoints within 3 kmTienne du Lion
- 36marked hiking routes within 3 kmGRP 125 Tour de l'Entre-Sambre-et-Meuse, Le Tienne Breumont, Les Abannets and 33 more
- 1climbing crags within 3 kmCarrière Sainte-Barbe
- 41car parks within 2 km
- 7information boards and visitor centres within 3 km
- 41bus stops within 2 km
- 9campsites within 8 kmBivouac des Trois Fontaines, Bivouac de Boussu-en-Fagne, Bivakzone Ry de Rome and 6 more
- 12hotels and guesthouses within 8 kmDomaine Saint Roch, La Calestienne, Les Sittelles and 9 more
- 11restaurants and cafés within 3 km
- sinkholes within 3 km
- caving clubs and spots within 15 km
- named waterfalls within 4 km
Counted in OpenStreetMap, the map anyone can edit, around the entrance. A low number may just mean nobody has mapped it yet. © OpenStreetMap contributors (ODbL).
Towns nearby
- Frasnes1.6 km in a straight line
- Petigny1.8 km in a straight line
- Couvin1.9 km in a straight line
- Nismes2.7 km in a straight line
- Mariembourg3.3 km in a straight line
- Baileux11 km in a straight line
- Neuville12 km in a straight line
- Cul-des-Sarts12 km in a straight line
In our other atlases
What else is around Neptune Caves.
The river at the entrance, the waterfalls, the lakes, the mountains and volcanoes above, the canyons, beaches and islands nearby — from our other atlases.
Riveryas1 rivers at the entranceFigures from the sister sites' databases (Wikidata, HydroATLAS, GeoNames, NOAA, OpenStreetMap). Links open when each site is online.
Month by month
The weather outside, at the entrance.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Afternoon | 4 | 5 | 10 | 14 | 18 | 21 | 23 | 22 | 19 | 14 | 9 | 5 |
| Afternoon | 4 | 5 | 10 | 14 | 18 | 21 | 23 | 22 | 19 | 14 | 9 | 5 |
| Night | -1 | -1 | 1 | 4 | 8 | 11 | 13 | 13 | 9 | 6 | 3 | 0 |
| Rain (mm) | 82 | 71 | 68 | 49 | 70 | 71 | 73 | 80 | 54 | 70 | 78 | 93 |
| Rainy days | 14 | 13 | 13 | 11 | 14 | 14 | 14 | 13 | 11 | 13 | 15 | 16 |
| Sun hours/day | 1.3 | 2.4 | 4.2 | 6.3 | 6.7 | 7.1 | 7.0 | 6.2 | 5.5 | 3.5 | 1.6 | 1.0 |
| Snow on the ground (cm) | 11 | 11 | 5 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 3 | 10 |
| Afternoon | Afternoon | Night | Rain (mm) | Sun hours/day | |
|---|---|---|---|---|---|
| Jan | 4 | 4 | -1 | 82 | 1.3 |
| Feb | 5 | 5 | -1 | 71 | 2.4 |
| Mar | 10 | 10 | 1 | 68 | 4.2 |
| Apr | 14 | 14 | 4 | 49 | 6.3 |
| May | 18 | 18 | 8 | 70 | 6.7 |
| Jun | 21 | 21 | 11 | 71 | 7.1 |
| Jul | 23 | 23 | 13 | 73 | 7.0 |
| Aug | 22 | 22 | 13 | 80 | 6.2 |
| Sep | 19 | 19 | 9 | 54 | 5.5 |
| Oct | 14 | 14 | 6 | 70 | 3.5 |
| Nov | 9 | 9 | 3 | 78 | 1.6 |
| Dec | 5 | 5 | 0 | 93 | 1.0 |
Averages 1991–2020 (NASA POWER) for a cell about 55 km wide, brought to the altitude of the entrance (180 m) with the standard lapse rate. Not a forecast.
Recent years
Wet years, dry years.
Rain of each month as a share of the 1991–2020 average. A dry year means a lower river and hotter rock; a wet one, more water in the gorge.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 2020 | 73% | 197% | 106% | 46% | 30% | 92% | 45% | 42% | 125% | 155% | 47% | 126% |
| 2021 | 136% | 72% | 69% | 71% | 99% | 158% | 226% | 94% | 81% | 125% | 55% | 91% |
| 2022 | 83% | 106% | 38% | 93% | 42% | 158% | 22% | 29% | 197% | 107% | 100% | 114% |
| 2023 | 157% | 28% | 218% | 162% | 72% | 94% | 170% | 135% | 170% | 186% | 190% | 122% |
| 2024 | 159% | 216% | 152% | 196% | 220% | 160% | 157% | 89% | 243% | 168% | 97% | 94% |
| 2025 | 222% | 76% | 23% | 76% | 68% | 114% | 133% | 63% | 194% | 129% | 103% | 38% |
130% or more: wet month 70% or less: dry month
Caves nearby.
Neptune Caves
Belgium
- —Depth
- —Galleries
- 180 mEntrance altitude
- 10 °CInside, all year
Trou de l’Abîme
Belgium · 2 km
- —Depth
- —Galleries
- 185 mEntrance altitude
- 10 °CInside, all year
Caves of Han-sur-Lesse
Belgium · 49 km
- —Depth
- —Galleries
- 155 mEntrance altitude
- 10 °CInside, all year
Grotte de Spy
Belgium · 47 km
- —Depth
- —Galleries
- 125 mEntrance altitude
- 10 °CInside, all year
Where these figures come from
| Name, type, published depth and length, visitors | Wikidata (Q2662680) · CC0 |
|---|---|
| The relief above, the entrance altitude, the section and the 3D model | Copernicus DEM GLO-30 · © DLR e.V., © Airbus Defence and Space GmbH, Copernicus/ESA |
| River flow and basin | HydroATLAS / RiverATLAS v1.0 (Linke et al. 2019) · CC BY 4.0 |
| Climate | NASA POWER, 1991–2020 |
| Entrances, springs, sinkholes, opening hours and what is around | © OpenStreetMap contributors · ODbL |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
| Rivers, waterfalls, lakes, mountains, canyons, beaches and islands nearby | Coastya, Lakeyas, Peakyas, Cascadyas, Islandyas, Riveryas |
Every figure is an average, an estimate or a count from a public dataset. Licences and methods: data sources.
The family
Do you prefer beaches, lakes, mountains, waterfalls, islands, rivers, canyons, caves, dark skies, viewpoints, birdwatching or forests?
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