Lake Toba sits at 911 metres above sea level in the heart of northern Sumatra. It stretches a hundred kilometres long, thirty wide and over five hundred metres deep. At first glance, it looks more like an inland sea than a lake — and in a sense, that is exactly what it is. It was formed by one of the largest volcanic eruptions in the history of the planet.
The supervolcano that changed the world
Roughly 74,000 years ago, a supervolcano erupted here with such force that its ash blanketed all of Southeast Asia and likely triggered a global cooling lasting several years. The caldera left behind gradually filled with water, creating the largest volcanic crater lake in the world.
Today, Toba is a calm and quiet place. The surrounding hills reflect on the surface, mist rises from the water in the morning and the kind of silence hangs over the area that you rarely find in Indonesia. It is one of the contrasts that make Sumatra so compelling — beneath the tranquil surface lies immense geological power.
Samosir Island — an island within a lake
In the middle of Lake Toba lies Samosir Island, roughly half the size of Prague. Samosir is a geological curiosity in its own right — an island inside a crater lake, formed by a secondary volcanic uplift after the main eruption.
Samosir is the main destination for most visitors. This is where you will find Batak villages, traditional houses with their distinctive saddleback roofs, royal tombs and small museums that tell the story of Batak history and customs.
You can easily spend several days on Samosir — walking through villages, swimming in the lake, cycling around the island or simply sitting on a terrace watching the water. It is a place where time naturally slows down.
Batak culture
The Batak people are one of the most distinctive ethnic communities on Sumatra. Their culture is rich, unique and very much alive. Houses with high saddleback roofs (rumah adat) stand in villages across the lake region. The woodcarvings on their facades tell stories of clans and traditions.
The Batak went through a wave of Christian missionary activity, but their original customs and rituals have endured. On Samosir you can watch the traditional Tor-Tor dance, visit the stone tombs of the Siallagan kings or learn about the significance of ulos — traditional woven textiles that play a role in every major life event.
For travellers interested in culture and history, the area around Toba is one of the most fascinating places in all of Indonesia.
What to experience at Toba
Hot springs at Pangururan. On the western side of Samosir, sulphur springs emerge directly from the volcanically active bedrock. They are freely accessible and bathing in them is one of the quiet pleasures of a stay at Toba.
Traditional villages of Ambarita and Tomok. Ambarita is known for its stone seats where trials were once held. Tomok offers the stone tomb of King Sidabutar and a small market with local crafts.
Cycling around Samosir. The island is small enough to circle in a day by bicycle. The route passes through rice fields, villages and along the lakeshore.
The view from Tele lookout. If you are driving from Medan via Brastagi, stop at the lookout above the lake. From there you can see the entire caldera in its true scale — and understand why locals call Toba “the sea in the middle of the mountains.”
How to reach Lake Toba
From Medan, the capital of North Sumatra, the road to the lake leads through the town of Parapat, where you take a ferry to Samosir. The drive takes approximately four to five hours, depending on traffic.
If you are travelling on a longer circuit around northern Sumatra, Toba fits naturally into the route between Bukit Lawang (rainforest trek to see orangutans) and Brastagi (volcanic highlands). This combination — rainforest, lake, volcanoes — is one of the great strengths of the region.
The ferry from Parapat to Samosir runs regularly and the crossing takes about 45 minutes. On Samosir, you dock at Tuk Tuk, the island’s main tourist hub.
Where to stay
On Samosir you will find accommodation ranging from simple guesthouses to comfortable hotels with lake views. Most options are clustered around the Tuk Tuk peninsula on the eastern side of the island.
For trips organised with Simply Horas, we select accommodation we know personally — places with character, clean and safe, with views of the lake and within reach of the main sights.
Practical tips
- Weather: The area around Toba sits higher than the rest of Sumatra. Evenings and mornings can be cooler — bring a light jacket.
- Length of stay: We recommend at least two nights on Samosir. Anything less and you will not have time to absorb the atmosphere of the place.
- Money: There are ATMs in Parapat and on Samosir, but it is wise to carry cash. Smaller places do not accept cards.
- Alcohol: The Toba area is one of the few parts of Sumatra where alcohol is widely available — the Batak are predominantly Christian.
- Respect: When visiting traditional villages and tombs, be mindful. Photography is usually fine, but ask first.