The Selangor River estuary holds one of Southeast Asia's densest populations of Pteroptyx tener, a synchronous firefly species that colonizes berembang trees in concentrations exceeding 200 beetles per square metre during peak season. First documented by British naturalist Herbert Christopher Robinson in 1903, the phenomenon remained a subsistence curiosity for kampung fishermen until the Selangor State Forestry Department gazetted a 24-hectare conservation corridor in 1976. By 2010, Kampung Kuantan had formalized the traditional sampan routes into a managed ecotourism program, now supporting 47 licensed boatmen and generating 1.2 million ringgit annually for the village cooperative. The attraction pairs two distinct wildlife encounters. Eagle feeding occurs at the river mouth during the golden hour, when boatmen scatter anchovies to draw Brahminy kites and white-bellied sea eagles from their roosts along the mangrove edge. The practice, adapted from traditional fishing methods, allows close observation of raptors in active hunt behavior—wingspans reach two metres, and the birds descend within three metres of the boat. As twilight deepens, sampans motor upstream into narrower tributaries where firefly colonies concentrate. The beetles emit bioluminescent flashes at 560 nanometres, producing a synchronized pulse visible up to 30 metres. Peak luminosity occurs between 20:00 and 21:30, when male beetles synchronize their flash intervals to attract mates. On moonless nights, the cumulative glow can illuminate mangrove canopies in a shifting green corona. Kuala Selangor fireflies and eagle feeding tour departures operate year-round, though November through February offers optimal conditions—lower tides expose more riverbank hunting grounds for eagles, and reduced ambient light sharpens firefly visibility. The berembang groves remain intact due to a 1998 moratorium on coastal clearing, which preserved the specific soil salinity and tidal rhythm the beetles require. Water quality monitoring since 2004 confirms stable pH and dissolved oxygen levels, critical markers for the ecosystem's resilience. Recent additions include bioluminescent plankton displays—Noctiluca scintillans blooms that trail the boat hull in electric blue wakes, a seasonal phenomenon occurring March through May when monsoon runoff enriches estuarine nutrients.