Derawan Archipelago (Derawan, Sangalaki, Kakaban, Maratua)

What makes it special

• Sangalaki's Manta Parade and Manta Run — described in the Important Shark and Ray Areas assessment as the only known reef manta cleaning stations in east Borneo, with 123 photo-identified individuals and feeding aggregations of up to 42 rays
• Indonesia's largest green turtle nesting area: around 15,000 clutches a year across the archipelago, with Sangalaki alone historically producing about a third of the eggs
• Kakaban's landlocked marine lake, holding four stingless jellyfish species (Mastigias, Aurelia, Tripedalia and Cassiopea) — snorkel-only, and reopened in early 2025 after a population crash
• The Maratua atoll channel, locally called Big Fish Country, where chevron barracuda and bigeye trevally school at the mouth on tidal flow

Best time to dive

Current

Moderate

Water temp

28–30.5°C (coldest Jan, warmest Apr)

Visibility

8–30m — Commonly around 20m, with 8m on a bad day. The plankton that feeds the Sangalaki mantas cuts visibility, and outflow from the Berau river system on the mainland can push it down further after heavy rain.

Getting there

Moderate — Reachable but with some friction: 1 domestic flight, a 2.5h overland transfer, a 2h boat crossing.

Experience

Most of the archipelago is approachable at Open Water level — the Sangalaki manta sites are shallow and usually mild, and the Derawan house reef is a walk-in. Two sites are different: the Maratua atoll channel and Kakaban's Barracuda Point run hard current, reef hooks are standard practice at Barracuda Point, and operators expect Advanced Open Water plus real current experience before taking you there.

Nearest airports

• BEJ — Kalimarau Airport (Berau / Tanjung Redeb) (The practical arrival airport; domestic flights from Balikpapan (BPN) or Jakarta, then a road-plus-speedboat transfer to Derawan or a speedboat from the Berau river jetty to Maratua)
• BPN — Sultan Aji Muhammad Sulaiman Sepinggan International Airport (Balikpapan) (Nearest international airport, with direct services to Singapore and Kuala Lumpur; connect onward to Berau (BEJ))
• RTU — Maratua Airport (Small airstrip on Maratua itself, served only by a short Wings Air hop from Berau (BEJ); schedules are thin and change often)

Sightings are never guaranteed — the bars show typical likelihood by month.

Dive sites

Worth knowing before you book

• Access is the real cost. Nearest international airport is Balikpapan; from there it is a domestic flight to Berau (BEJ), then either a 2-2.5h road transfer to Tanjung Batu plus a 30-minute boat to Derawan, or a 2.5-3h speedboat from the Berau river jetty to Maratua. Boats are weather- and tide-dependent and the last one normally leaves before mid-afternoon, so a late arrival means an unplanned night in Berau.
• Kakaban's jellyfish lake is not something to build a trip around right now. It closed on 23 December 2023 after the jellyfish largely disappeared — chemical contamination from swimmers' sunscreen and lotion is the explanation officials have given — and reopened in early 2025. Reporting since conflicts: some 2025-2026 sources describe supervised snorkelling under strict rules (no sunscreen, no fins, no scuba, capped group size), others describe an outright swimming ban with viewing from the boardwalk only.
• The Talisayan whale sharks are food-attracted animals around bagan lift-net fishing platforms, roughly two hours by boat from Derawan, snorkel-only, on a 5am start that costs you a day's diving. WWF Indonesia publishes a code of conduct that bans feeding, touching and chasing, and also notes that operators have not consistently implemented those standards. If a provisioned interaction sits badly with you, skip it.
• The islands are far apart and day boats cover the distances slowly. Operators commonly set minimum booked stays to guarantee the longer runs — one dive centre asks for six days of diving to guarantee Maratua and four to guarantee Kakaban — and trips get cancelled for weather.
• The turtle population is recovering, not recovered. Published monitoring has Sangalaki nesting averaging about 57% of 1995-2000 levels and Derawan about 26% of its 1985-1990 baseline, after decades of commercial egg harvesting.