When the mantas show up, when the jellyfish are dense.
Derawan diving runs year-round but conditions vary. Here’s the seasonal calendar that drives our departure schedule. (See Derawan Islands for context.)
Derawan sits 2° north of the equator. Climatologically, it has wet and dry seasons but they are mild — there’s no hard “closed” season the way Raja Ampat or Wakatobi shut down. What changes month to month is visibility, wind, and the specific marine activity that draws photographers here.
The honest calendar
| Month | Conditions | Manta sightings | Jellyfish density |
|---|---|---|---|
| January-Feb | Calm, vis 25-30m. Light NW wind. | High (90%+) | Peak — millions visible |
| March-April | Best viz of the year (30-40m). | Very high | Peak |
| May-June | Slight wind, vis 22-28m. | High | High |
| July-Aug | SE monsoon, vis 18-22m. Rough crossings. | Moderate | Stable |
| Sept-Oct | Transitioning. Wind dropping. | Increasing | Building |
| Nov-Dec | Good. Vis 25-28m. Manta numbers building. | High | High |
Best month, our pick: March
First three weeks of March consistently produce the best combination — peak manta sightings, near-best visibility, calm crossings, and turtle nesting season starting. Liveaboards sell out in March 4-6 months ahead.
When NOT to come
Mid-July through August has the SE monsoon — wind 25-30 knots, rough crossings between Maratua and Sangalaki. We don’t run our standard route in those weeks. Some operators do shorter Maratua-only trips, but the value is reduced.
Shoulder season: October/November
For repeat visitors who don’t need peak conditions, October’s first half offers similar-quality diving at 15-20% lower pricing and 60% lower bookings. We send second-time clients here.
Match my dates to conditions
Tell us your travel window and we’ll tell you what you’ll see. Honest seasonal advice.
