A survey on the congregating fireflies located in the mangrove forest of Sungai Kawang, Kinarut, 20 kilometers south of Kota Kinabalu was conducted from September to October 2015. The dominant firefly species was Pteroptyx bearni Olivier. Out of 133 male Pteroptyx fireflies collected, 131 individuals belong to this species. The less common species Pteroptyx malaccae Gorham was collected on a mangrove tree that is away from the jetty. Most of the fireflies were collected from the dominant mangrove species, Rhizophora mucronata, while some were collected from Aegiceras floridum and Lumnitzera littorea. With a high population of congregating fireflies and the geographical advantages of Sungai Kawang, it has the potential to be developed as a tourist attraction. Proper development planning associated with a system for population monitoring and habitat conservation are essential for sustainable ecotourism.