2 .In northern Sumatra Lake Toba. Who does not know the Lake Toba Lake Toba is the most well-known and widespread in Indonesia because of the unique shape of the presence of an island in the middle of Lake Toba. With a length of about 100 KM and 30 KM wide sektiar, Lake Toba is the largest volcanic lake in Southeast Asia. Lake Toba is a tourist spot in North Sumatra, the most famous, not to worry if you want to stay in Lake Toba as along the shores of Lake Toba there are many inns.