If you are in Indonesia, do visit this "lake within a lake" - Lake Sidihoni. Located within Samosir Island, this place is an island within Lake Toba, in North Sumatra, which is about 20 hectares. The lake is surrounded by green hills and pine trees, which offers a refreshing and cool environment. An ideal place to visit with family and friends, the lake also offers a unique experience as it can alter its color depending on the weather conditions. Entry to Lake Sidihoni is free and you can visit anytime of the year.