What is coffee from Samosir Island, Indonesia? Coffee discovered on an island floating in Lake Toba
Lake Toba, one of the world's largest caldera lakes, is located in northern Sumatra, Indonesia.
The massive island floating in the center of this lake is **Samosir Island**.
Sumatran coffees like Mandheling and Lintong are well-known in Japan. However, "Samosir" as a coffee producing region may not yet be familiar to many people.
In August 2026, 0566 Coffee Works actually visited Samosir Island, touring farms and processing plants.
This time, we will introduce Samosir coffee, incorporating our experiences of what we saw, heard, and tasted there.
Where is Samosir Island?
Samosir Island is an island in Lake Toba, North Sumatra Province, Indonesia.
Lake Toba itself is a caldera formed by a massive volcanic eruption, and Samosir Island lies within it.
Coffee cultivation is one of Samosir's important agricultural industries.
According to Samosir Regency Government documents, Ronggur Nihuta, Pangururan, and Palipi are introduced as major coffee producing areas.
The farm we visited in Ronggur Nihuta was located at an altitude of approximately 1,530m.
Since the surface of Lake Toba is about 900m, coffee was cultivated on a high-altitude area about 600m above the lake.
Coffee cultivated in Samosir
The main varieties identified locally were:
Sigarar Utang
Aten Super
and others.
Sigarar Utang, in particular, is one of North Sumatra's representative Arabica varieties.
The name "Sigarar Utang" means "to repay debts" in the local language.
It is said to have been named this because it bears fruit relatively quickly, shortening the period until farmers can generate income.
Coffee is not merely a luxury item.
When you visit producing regions, you realize that it is deeply intertwined with the daily lives of the people who live there.
Is all Samosir coffee "Mandheling"?
In Japan, coffee from northern Sumatra is sometimes broadly recognized as "Mandheling."
However, when you actually walk through the producing regions, it's not that simple.
The individuality of coffee changes depending on the region, altitude, variety, farmer, and processing method.
0566 Coffee Works believes that Samosir is also worth viewing as an independent producing region.
FAO documents also mention multiple regions around Lake Toba as Arabica producing areas in North Sumatra, including Samosir, Toba Samosir, North Tapanuli, and Humbang Hasundutan.
In other words, within the broad names of "Sumatra" and "Mandheling," there are even more nuanced differences in producing regions.
Four processing methods confirmed in Samosir
At the processing plant we visited, the following different processing methods were being used:
・Sumatran method (Giling Basah)
・Fully washed
・Natural
・Honey
This was a very interesting point.
Not only the traditional Sumatran method but also naturals, honeys, and fully washed coffees, with an eye on the specialty coffee market, were being produced.
In reality, even from the same Samosir origin, the flavor varies greatly depending on the processing method.
Fully washed coffees tend to exhibit a clear acidity and transparency, while naturals have a strong fruitiness and sweetness.
Honey processing aims for a balance of sweetness and fruitiness, falling somewhere in between the other two.
And the traditional Sumatran method produces a rich body and unique complexity.
It's not "the same taste if the origin is the same."
This is also what makes coffee so interesting.
The problem of "drying" that caught our attention locally
During this visit, 0566 Coffee Works particularly focused on the **drying process**.
In Samosir, there is strong sunlight during the day.
However, in the early morning, mist and low clouds form around Lake Toba.
In fact, on the morning we were there, we observed low clouds flowing from the caldera rim into the caldera itself.
For coffee drying, it's not just about whether the sun is out during the day; humidity from night to early morning is also crucial.
Especially for naturals, where the entire cherry is dried for a long period, repeated drying and re-absorption of moisture can affect quality.
Some lots of green beans purchased locally showed color variations.
Of course, this alone cannot definitively determine the cause.
However, 0566 believes that for producing higher quality coffee in Samosir, **managing the drying environment will be a crucial theme**, in addition to variety and fermentation.
What is the "Samosir-like taste"?
We don't have an answer to this yet.
That's what makes it interesting.
In the world of specialty coffee, vibrant fermentation and intense fruit flavors sometimes receive a lot of attention.
However, 0566 Coffee Works is not looking for merely showy flavors.
We seek a taste that can only be experienced from coffee grown in the land of Samosir.
Altitude, climate, variety, soil, processing.
We aim to preserve these elements as faithfully as possible in the cup.
Therefore, we will also roast the coffee brought back from the origin in Japan and verify the differences among the processing methods.
Beyond the coffee is the "land"
The reason we visit producing regions is not just to find rare beans.
It's because we believe that only by understanding:
where the coffee was grown,
who produced it,
how it was processed, and
why it tastes the way it does,
can we truly appreciate a cup of coffee.
0566 Coffee Works' exploration of Samosir Island coffee has just begun.
Going forward, we will continue roasting tests to discover "coffee that only Samosir can produce."
References / Sources of Information
・Samosir Regency Government "Potensi Unggulan Kabupaten Samosir – Perkebunan"
https://samosirkab.go.id/potensi-unggulan-kabupaten-samosir-perkebunan/
・FAO "Coffee Processing/Techniques in Tapanuli Utara, Humbang Hasundutan, and Toba Samosir District"
https://www.fao.org/fileadmin/user_upload/agns/pdf/coffee/Annex-E.5.pdf
*Some descriptions regarding farm altitude, local processing conditions, and climate/drying environment are based on field surveys, interviews, and observations conducted by 0566 Coffee Works during their visit to Samosir Island in August 2026.
