Koh Rong plankton: 20:00 or 22:00 tour?
Swim off Long Set Beach or from night boat trips on Koh Rong Samloem. Bioluminescence is only visible in real darkness, so the moon and the end of twilight decide which tour is worth it. Pick your date.
Mon 2 November 2026
Book the 20:00 tour
Darkness 5/5 ●●●●● · moon down, sky dark
| 20:00 tour | ●●●●● Pitch dark | moon down, sky dark |
|---|---|---|
| 22:00 tour | ●●●●● Pitch dark | moon down, sky dark |
Sunset 17:43 · Fully dark 18:54 · Moonset 12:42, rises 00:42 next day · Moon 41% lit (last quarter)
Next 30 nights
| Night | Moon | 20:00 | 22:00 | Best |
|---|---|---|---|---|
| Mon 2 Nov | 41% | ●●●●● | ●●●●● | 20:00 |
| Tue 3 Nov | 30% | ●●●●● | ●●●●● | 20:00 |
| Wed 4 Nov | 20% | ●●●●● | ●●●●● | 20:00 |
| Thu 5 Nov | 12% | ●●●●● | ●●●●● | 20:00 |
| Fri 6 Nov | 6% | ●●●●● | ●●●●● | 20:00 |
| Sat 7 Nov | 2% | ●●●●● | ●●●●● | 20:00 |
| Sun 8 Nov | 0% | ●●●●● | ●●●●● | 20:00 |
| Mon 9 Nov | 0% | ●●●●● | ●●●●● | 20:00 |
| Tue 10 Nov | 2% | ●●●●● | ●●●●● | 20:00 |
| Wed 11 Nov | 6% | ●●●●● | ●●●●● | 20:00 |
| Thu 12 Nov | 11% | ●●●●● | ●●●●● | 22:00 |
| Fri 13 Nov | 18% | ●●●●● | ●●●●● | 22:00 |
| Sat 14 Nov | 25% | ●●●●● | ●●●●● | 22:00 |
| Sun 15 Nov | 34% | ●●●●● | ●●●●● | 22:00 |
| Mon 16 Nov | 43% | ●●●●● | ●●●●● | 22:00 |
| Tue 17 Nov | 53% | ●●●●● | ●●●●● | 22:00 |
| Wed 18 Nov | 63% | ●●●●● | ●●●●● | 22:00 |
| Thu 19 Nov | 73% | ●●●●● | ●●●●● | 20:00 |
| Fri 20 Nov | 82% | ●●●●● | ●●●●● | 20:00 |
| Sat 21 Nov | 89% | ●●●●● | ●●●●● | 20:00 |
| Sun 22 Nov | 95% | ●●●●● | ●●●●● | 20:00 |
| Mon 23 Nov | 99% | ●●●●● | ●●●●● | 20:00 |
| Tue 24 Nov | 100% | ●●●●● | ●●●●● | 20:00 |
| Wed 25 Nov | 98% | ●●●●● | ●●●●● | 20:00 |
| Thu 26 Nov | 94% | ●●●●● | ●●●●● | 20:00 |
| Fri 27 Nov | 88% | ●●●●● | ●●●●● | 20:00 |
| Sat 28 Nov | 79% | ●●●●● | ●●●●● | 20:00 |
| Sun 29 Nov | 69% | ●●●●● | ●●●●● | 20:00 |
| Mon 30 Nov | 57% | ●●●●● | ●●●●● | 20:00 |
| Tue 1 Dec | 46% | ●●●●● | ●●●●● | 20:00 |
Season
Year-round; best in the dry season.
Koh Rong plankton darkest nights by month
How the darkness score works
For each tour slot we follow the sky for 90 minutes. Twilight scores against you until the sun is 18° below the horizon. The moon counts in proportion to how much of it is lit and how high it is. 5 means pitch dark; 1 means the glow will be hard to see. Clouds, rain and the health of the plankton also matter and are not in the score.
Times are local (Asia/Phnom_Penh). Calculated, not observed; tour operators set the real departure times.