Crater lake · Japan
Lake Mashū
Crater lake in Japan
- Area
- 18.7km²
- Max depth
- 212m
- Average depth
- 117m
- Elevation
- 347m a.s.l.
- Shoreline
- 20km
- Volume
- 2.2km³
Lake Mashū is a crater lake in Japan. It covers 18.7 km². On average it is 117 m deep, and 212 m at its deepest point. Its surface lies 347 m above sea level.
Plan your visit
Stay, sail and get there
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The water
How warm is Lake Mashū?
The water is warmest in August, around 18 °C at the surface, and coldest in February, around 0 °C. It rarely averages 20 °C, but it stays above 17 °C in August: brisk, refreshing swimming.
The lake usually freezes over for about 67 days a year, from around 27 January to 3 April.
On the shore, afternoons reach 23 °C on average in August and -5 °C in January. The driest month is February (35 mm of rain), the wettest August (138 mm).
Average surface temperature measured by the Landsat 8 satellite between 2013 and 2021 at the point furthest from the shore (116 readings). Shallow bays and beaches are often warmer.
From above
The whole lake from space
Month by month
The year at the lake, month by month
Not a forecast: these are averages over many years. Water is the 2013–2021 average; air, rain, sun and wind are the 1991–2020 average.
Water: 2013–2021 averageClimate: 1991–2020 average
| Month | Water°C | Water high°C | Air high°C | Air low°C | Rainmm | Rainy daysdays | Sunh/day | Windkm/h |
|---|---|---|---|---|---|---|---|---|
| January | 1 | 2 | -5 | -14 | 45 | 10 | 4.7 | 14 |
| February | Ice | — | -4 | -14 | 35 | 7 | 5.8 | 15 |
| March | Ice | — | 0 | -7 | 52 | 9 | 5.9 | 17 |
| April | 1 | 3 | 7 | -1 | 63 | 10 | 5.9 | 16 |
| May | 5 | 8 | 13 | 5 | 89 | 11 | 5.8 | 14 |
| June | 11 | 13 | 18 | 10 | 101 | 12 | 5.2 | 12 |
| July | 15 | 17 | 22 | 14 | 114 | 13 | 4.5 | 11 |
| August | 18 | 18 | 23 | 16 | 138 | 13 | 4.4 | 11 |
| September | 17 | 18 | 19 | 12 | 121 | 13 | 4.8 | 12 |
| October | 13 | 15 | 12 | 5 | 106 | 11 | 4.9 | 13 |
| November | 8 | 10 | 5 | -2 | 68 | 11 | 4.1 | 13 |
| December | 3 | 5 | -2 | -11 | 64 | 10 | 4.0 | 12 |
Water: LakeTEMP (Landsat 8, 2013–2021). Air, rain, sun and wind: NASA POWER, 1991–2020 averages. A rainy day has at least 1 mm of rain. Sunshine hours are derived from measured solar radiation.
Size & depth
How big, how deep
- On average, water stays in the lake for about 82 years before flowing out.
- Its catchment drains 41 km² of land.
- About 0.9 m³ of water flow out every second, on average.
Around the shore
What's around Lake Mashū
Counted within 1.5 km of the shoreline in OpenStreetMap, the map anyone can edit.
- —beaches and swimming spots
- —campsites
- —boat hire and water-sport clubs
- —marinas and slipways
- —ferry piers
- 3viewpoints
Ura-Mashu Observatory, Lake Mashu 1st Observatory, Lake Mashu 3rd Observatory
- —hotels, B&Bs and chalets
- —fishing spots
- 1restaurants and cafés
Nearest airport with scheduled flights: Nakashibetsu Airport (SHB), 35 km in a straight line.
Car hire at MMB airport (Ōzora)Discover Cars · Affiliate linkOpenStreetMap is built by volunteers: when a number is low, it may just mean nobody has mapped it yet.
Photos
Seen by visitors
Recent years
How each month compared
Afternoon high on the shore. The first row is the reference, the 1991–2020 average in °C; the years below show the difference from it: warmer in orange, cooler in blue.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec | |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| 1991–2020 average | -5.0 | -4.2 | 0.3 | 7.0 | 13.4 | 18.0 | 21.5 | 22.7 | 19.0 | 12.4 | 4.9 | -2.3 |
| 2020 | +1.3 | +0.2 | +1.9 | −1.3 | +1.0 | +0.3 | −0.4 | +2.1 | +0.4 | +0.8 | +0.6 | −0.8 |
| 2021 | −0.4 | +1.4 | +2.5 | +1.0 | −0.7 | +2.5 | +3.0 | −0.2 | −0.8 | +0.5 | +1.7 | +1.8 |
| 2022 | +0.1 | ±0.0 | +0.8 | +2.9 | +1.7 | −1.0 | +2.2 | −0.3 | +1.3 | +0.3 | +2.1 | +0.4 |
| 2023 | −1.2 | −0.4 | +3.7 | +1.9 | +2.0 | +2.3 | +3.5 | +2.8 | +3.1 | +1.4 | +2.4 | +0.1 |
| 2024 | +1.5 | +0.2 | −0.1 | +3.2 | +1.7 | +1.7 | +4.3 | +2.5 | +1.4 | +2.3 | +0.7 | −1.0 |
| 2025 | +2.0 | +1.4 | +0.3 | +0.9 | +1.7 | +3.8 | +5.2 | +1.8 | +2.1 | −0.9 | −0.1 | +1.4 |
+1 warmer than usual −1 cooler than usual
About these numbers
| Outline, area, depth, volume | HydroLAKES v1.0 (Messager et al. 2016) · CC BY 4.0 |
|---|---|
| Water temperature and ice | LakeTEMP v1 (Korver et al. 2024), Landsat 8 2013–2021 · CC BY 4.0 |
| Air, rain, sun, wind | NASA POWER, 1991–2020 · public domain |
| Names and description | Wikidata (Q1194619) · CC0 |
| Around the shore | © OpenStreetMap contributors · ODbL |
| Images | EOX Sentinel-2 cloudless 2016 · CC BY 4.0; Wikimedia Commons |
Every figure is an average or a count from a public dataset. Licences and methods: data sources.
