Roughly the size of Singapore, Pulau Samosir (Samosir Island) is a peaceful island situated within Sumatra’s Lake Toba — the largest volcanic lake in the world. Pulau Samosir was formed by the cone of a new volcano that rose up from the lake floor. Today, the island offers some fresh air, relaxation, and even headhunter culture for travelers who could use a break from Sumatra’s bumpy roads.

With gorgeous scenery, freshwater swimming in a naturally heated lake, and friendly Batak people, Pulau Samosir is the kind of hard-to-leave place that destroys itineraries! The summer months are typically the driest and are high season for Lake Toba and Pulau Samosir, although the entire area is in a major tourism slump at the moment. ​July is the peak of the busy season.
The primary tourist area on Pulau Samosir is a knob of land jutting from the island known as Tuk-tuk. A single road runs around Tuk-tuk in a complete circle; Tuk-tuk can be circumnavigated in around an hour on foot. One main road circles Pulau Samosir, while many poorly maintained roads crisscross through the island interior.

Tuk-tuk is reached by boat; ferries run regularly from the mainland and drop passengers at the guesthouses of their choice.

Much to the shock of backpackers arriving by boat, guesthouses on Pulau Samosir tend to be large, resort-like affairs with rooms offering beautiful views of the lake. Don’t be put off by the sanitized, package-holiday appearance — clean rooms with a lake view can be found for between $6 – $15 per night!

Source: https://www.tripsavvy.com/guide-to-pulau-samosir-1458485