Ten people were rescued after the boat carrying 25 people capsized between the Lombok and the Komodo islands on Saturday evening, hours after the accident in the early morning.
Those rescued hailed from New Zealand, France, Britain, Spain, the Netherlands and Germany.
The five Indonesians rescued included four boat crew members and a tour guide.
As of yet, the nationalities of those missing have not been disclosed.
Indonesia has a dismal maritime safety record even though it depends heavily on boats to connect its more than 17,000 islands.