Best Time to Visit the Derawan Islands 2026

Weather in East Kalimantan’s Derawan Archipelago, covering Derawan, Maratua, Sangalaki and Kakaban, follows a fairly predictable monsoon pattern, but the practical impact on a trip varies by what you’re actually planning to do once you arrive. This guide focuses on timing specifically for divers and snorkelers deciding between the archipelago’s shoulder and peak months, rather than giving one blanket recommendation that ignores what differs between diving, beach time and the jellyfish lake at Kakaban.

It also assumes you have at least some flexibility in your dates. If your travel window is fixed well in advance, by school holidays, work leave, or a connecting trip elsewhere in Indonesia, the more useful question is usually not which month is best in the abstract, but what to expect and plan around during whichever month you already have.

Independent seasonal guide, updated for the 2026 season. Conditions vary year to year, so treat this as a planning baseline rather than a guarantee, and check current marine forecasts closer to your travel dates.

That one-line answer covers most travelers, but the detail below matters more if your trip centers on a specific goal, a particular wildlife encounter, a calm-water swim at Kakaban, or simply the cheapest flights you can find, since each of those points toward a slightly different month.

The Two Seasons

Like much of maritime Southeast Asia, the Derawan Archipelago’s year splits broadly into a drier, calmer season from roughly April to October, and a wetter, rougher northwest monsoon from November to March. The shift isn’t absolute, rain and swell can show up in the “dry” months too, but the general pattern holds well enough to plan around, and it lines up with the climate patterns described for the wider region by sources such as Wikipedia’s Derawan Islands overview.

The practical effect of the monsoon season is less about rainfall directly on the islands, which tends to arrive in short, heavy bursts rather than constant drizzle, and more about sea state on the open crossings to Maratua and Tarakan, where wind-driven swell can delay or cancel boats.

East Kalimantan sits close enough to the equator that temperatures stay fairly constant year-round, generally in the high twenties to low thirties Celsius, so heat is rarely the deciding factor in when to go the way it might be for a temperate destination. Humidity is consistently high throughout the year as well, which matters more for comfort on the boat crossings than for diving itself.

Because the archipelago’s islands are small and low-lying, local microclimates can vary a little between Maratua, Derawan and Kakaban even on the same day, so a rainy morning on one island doesn’t necessarily mean the same conditions elsewhere in the group. Resort staff and boat captains, who cross these waters daily, are usually a better real-time read on conditions than any general seasonal guide, including this one.

Month-by-Month Notes

Within the calmer window, June through August draws the most visitors thanks to Northern Hemisphere summer holidays, so if you want the reliable weather without the busiest dive boats, May or September are worth prioritizing specifically.

Flight pricing into Berau and Tarakan tends to track the same holiday demand curve, so booking shoulder-season dates can save money on transport as well as on resort rates, on top of the lighter crowds. None of this is a hard rule; a well-timed trip in a nominally “off” month can still turn out calm, and a trip in a “safe” month can still run into a few rough days, but the averages are worth planning around.

Manta Season at Sangalaki

Manta rays visit Sangalaki’s cleaning stations across most of the year rather than on a tight migratory schedule, so there isn’t a single “manta month” the way there is at some other Indonesian sites. What changes seasonally is water clarity: the calmer April-to-October stretch generally gives better visibility for spotting and photographing mantas, while monsoon-season runoff and swell can reduce visibility even when the animals themselves are still present. Green turtle nesting activity, tracked at a species level by the IUCN Red List, also continues through most of the year around Sangalaki and Derawan’s beaches.

Early morning trips tend to produce calmer water and better light for manta encounters regardless of season, since afternoon wind can pick up even in the drier months. Most resorts schedule their Sangalaki day boats accordingly, leaving at or before sunrise, which is also worth keeping in mind if you’re not a naturally early riser: this is one trip worth setting an alarm for.

Kakaban’s Jellyfish Lake: Mostly Season-Proof

Because Kakaban’s stingless jellyfish lake is a sheltered, landlocked body of water rather than open sea, it’s much less exposed to monsoon swell than the dive sites around Maratua or the crossing itself. The bigger seasonal factor for a Kakaban day trip is simply whether your boat can safely make the crossing that day, covered in our dedicated Kakaban Jellyfish Lake guide, rather than conditions inside the lake itself.

That relative weather independence makes Kakaban a useful backup plan on a trip where rough seas have canceled a dive day elsewhere in the archipelago: if conditions allow even a short, careful crossing, the lake itself will usually still be calm and swimmable once you arrive.

Planning Around School Holidays and Booking Windows

Indonesian and international school holiday periods, especially July-August and the Christmas-New Year window, add demand on top of the weather pattern. Dive resorts on Maratua and Derawan can book out months ahead for these windows even though the underlying sea conditions in July-August are generally good, so treat calendar demand and weather as two separate planning factors rather than assuming good weather automatically means easy availability.

If your schedule is flexible, shoulder months like May and September let you capture most of the calm-season benefits while competing with fewer other travelers for boats, guides and resort rooms. Flights into Berau and Tarakan also tend to be easier to book, and sometimes cheaper, outside the main holiday peaks.

Divers chasing a specific target, a particular manta encounter, a calm-water Kakaban day, a quiet Maratua wall dive without other boats nearby, generally do better building a few flexible days into the itinerary rather than locking every day to a fixed plan, since weather on the ground can still shift day to day even within a good month.

How This Compares to Other Indonesian Dive Regions

The Derawan Archipelago’s seasonal pattern broadly tracks other Indonesian dive destinations like Komodo, though exact timing and the strength of the monsoon differ by location, since Indonesia spans a wide range of microclimates from Sumatra to Papua. If you’re weighing a Kalimantan trip against alternatives, our guides to Komodo National Park, Weh Island and Nias Island cover their own seasonal timing in more detail, and the official Wonderful Indonesia site is a reasonable cross-check for any region-wide weather advisories before you book flights.

Whichever month you land on, cross-referencing a specific resort’s current read on conditions is more useful than any general seasonal guide, this one included, since local wind and swell patterns around a single atoll can diverge from the broader regional pattern for stretches of a week or two at a time.

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