Sangalaki

Sangalaki is a Marine Nature Tourism Park (Taman Wisata Alam Laut) protecting a small coral island and its surrounding reefs in the Sulawesi (Celebes) Sea, part of the Derawan Archipelago off the coast of East Kalimantan, Indonesia. ^[1] Established on 19 August 1982 by Ministerial Decree No. 604/Kpts/Um/8/1982 and covering roughly 280 hectares (2.8 km²) of island and reef, it lies about 90 km offshore from Berau. The reserve is internationally renowned among divers for its resident reef manta rays (Mobula alfredi) and as a major nesting beach for green turtles (Chelonia mydas). Managed under Indonesia's KSDAE conservation system through the East Kalimantan BKSDA, Sangalaki balances marine tourism with strict protection of its turtle and manta populations.

Sangalaki's marine waters are known for aggregations of reef manta rays (Mobula alfredi), which gather to feed in the plankton-rich channels around the island, sometimes in groups of up to 20 individuals. ^[1] The beaches are one of the most important green turtle (Chelonia mydas) nesting sites in the region, with females hauling ashore year-round to lay eggs; hawksbill turtles also occur on the reefs. The surrounding coral gardens host abundant reef fish, cuttlefish, and mantis shrimp, and the area is part of the wider Derawan ecosystem. Seabirds and the occasional dugong frequent the shallow seagrass meadows nearby.

The island itself supports a low cover of coastal strand vegetation, including coconut palms, pandanus, beach morning glory, and salt-tolerant shrubs that stabilize the sandy turtle-nesting beaches. The dominant living systems, however, are marine: fringing coral reefs of branching, plate, and massive corals, along with seagrass beds and algae that underpin the food web. These seagrass and reef habitats are critical foraging grounds for green turtles and feeding stations for manta rays, making the underwater flora and benthic communities as important as the terrestrial vegetation.

Sangalaki is a small, low-lying coral cay formed atop a reef platform in the shallow tropical seas of the Derawan Archipelago. Like its neighboring islands, it sits on a carbonate foundation built up by reef-building corals over millennia, with beaches composed of fine white coral sand. The surrounding seafloor features reef slopes, sandy channels, and drop-offs that influence the currents bringing nutrient-rich water to the manta feeding areas. The archipelago's reefs and limestone formations are part of the broader Coral Triangle, a center of marine geological and biological richness.

The island has a hot, humid equatorial maritime climate with high temperatures year-round, typically in the upper 20s to low 30s Celsius. Rainfall is abundant and fairly evenly distributed, though influenced by the northwest and southeast monsoons, with calmer seas and clearer water generally favoring the drier intervals. Sea surface temperatures remain warm throughout the year, supporting coral growth, while seasonal plankton blooms drive the manta ray feeding aggregations that the park is known for.

The Derawan Archipelago has long been used by Bajau (sea nomad) and coastal Berau communities who fished and traveled these waters. Historically, turtle eggs from islands like Sangalaki were harvested for food and trade, a practice that contributed to declines in nesting populations before formal protection. The waters fall within the cultural and economic sphere of the Berau Regency, and local maritime communities retain strong ties to the sea, fishing, and increasingly to marine tourism that now provides livelihoods around the reserve.

Sangalaki was designated a Marine Nature Tourism Park on 19 August 1982 by Ministerial Decree No. 604/Kpts/Um/8/1982 to protect its turtle nesting beaches and surrounding reefs from egg collection and unregulated fishing. ^[1] Conservation efforts intensified as the site gained fame for its manta rays and green turtles, drawing dive operators and researchers. Management under the East Kalimantan BKSDA introduced turtle hatchery and monitoring programs, and the island became a flagship for marine protection in the Derawan complex, which has been proposed for broader conservation and World Heritage consideration.

The principal attractions at Sangalaki are entirely marine. Divers and snorkelers come for close encounters with reef manta rays (Mobula alfredi) at dedicated feeding and cleaning stations, and for the chance to watch green turtles glide over the reef. Night beach patrols to observe nesting turtles and, where permitted, hatchling releases are highlights for visitors. The nearby Derawan, Maratua, and Kakaban islands round out the experience, with Kakaban famous for its stingless jellyfish lake, making Sangalaki a key stop on a renowned dive circuit.

Reaching Sangalaki involves flying or driving to Berau (Kalimarau Airport, Tanjung Redeb), then taking a speedboat through the Derawan Archipelago, roughly 90 km offshore. The small island offers limited facilities, historically including basic dive-resort and ranger accommodation, with most visitors basing themselves on nearby Derawan or Maratua. Activities are dive- and snorkel-focused; visitors are expected to follow strict rules protecting turtles and mantas, including no touching, no flash near nesting turtles, and adherence to ranger guidance.

Conservation at Sangalaki centers on protecting green turtle nesting and reef manta ray (Mobula alfredi) populations, both listed as Vulnerable by the IUCN. ^[1] Management includes turtle egg protection, hatcheries, nest monitoring, and regulation of dive tourism to limit stress on mantas and reefs. The reserve forms part of wider efforts across the Derawan Archipelago to curb destructive fishing and turtle-egg trade while developing sustainable, community-linked marine ecotourism. Ongoing challenges include enforcement across a remote area, climate-driven coral bleaching, and balancing growing visitor numbers with the fragility of the ecosystem.