Sumatra and Sulawesi.
Kalimantan
Semarang
Sumatra Island
Sumatra Island
Batam Island is part of Indonesia and is located northwest of Jakarta.
Java
Singapore
Indonesia is not an island it is a country made up of many islands. Lake Towuti is a lake in South Sulawesi, Indonesia.
Sumatra Island
Yes, it is a proper noun. It is a large island in Indonesia.
Borneo