Satellite view of Koh Tao with approximate depth contours every 10 m

Koh Tao in September

September is outside the peak season in Koh Tao (best: Mar-May). Expect water around 29 °C at the surface and 29 °C at depth, with about 30 m of visibility.

Season
Off peak
Water
29 °C
Visibility
30 m
Waves
0.6 m
Species likely
398
Best sites for September AugustOctober
Koh Tao from Sentinel-2, 1 December 2025 · Contains modified Copernicus Sentinel data 2025; depth contours approximate (NOAA ETOPO 2022)
September at a glance

What September is like in Koh Tao.

Month grade from logged dives across 23 sites: visibility, sea state and sightings. Tap a month to compare.

Divegrade month grade, 0 to 10Best monthsOther months
September · Off peakOutside the best months (Mar-May)

Surface 29 °C, at depth 29 °C, visibility 30 m, waves about 0.6 m.

Peak seasonBest: March, April, May

Compare Koh Tao in March or see the whole year on the Koh Tao page.

Where to dive in September

Best dive sites in Koh Tao in September.

Ranked by Divegrade score for September. Each line shows the site's September conditions where divers have logged them.

Interactive map loads here. Every site on it is also listed on this page.

  1. 01Chumpon Pinnacle30 m viz · 29 °C · Advanced · 12-45 m8.5
  2. 02HTMS Sattakut30 m viz · 29 °C · Advanced · 18-31 m8.0
  3. 03White Rock30 m viz · 29 °C · Open Water · 2-26 m7.9
  4. 04Twins30 m viz · 29 °C · Beginner · 5-25 m7.8
  5. 05Green Rock30 m viz · 29 °C · Open Water · 4-32 m7.6
  6. 06Hin Ngam29 m viz · 29 °C · Beginner · 3-16 m7.6

Site list photos: (c) portioid, some rights reserved (CC BY), via iNaturalist (CC BY) · Leonard Low from Australia, via Wikimedia Commons (CC BY 2.0), Moon wrasse, taken elsewhere · (c) Dan Schofield, some rights reserved (CC BY), via Wikimedia Commons (CC BY 4.0) · (c) Jan Ebr & Ivana Ebrová, some rights reserved (CC BY), via Wikimedia Commons (CC BY 4.0) · Amada44, via Wikimedia Commons (CC BY SA 3.0) · (c) ig: underwater.logs, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) Jean Jacques Godon, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) Kat Lim, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) Jan Ebr & Ivana Ebrová, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) Gonzalo Ganda Álvarez, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) Shane Austin, some rights reserved (CC BY), via iNaturalist (CC BY) · (c) luluchouette, some rights reserved (CC BY), via iNaturalist (CC BY) · H. Schlegel, via Wikimedia Commons (PD), Doublebar Rabbitfish, taken elsewhere.

What you'll see in September

Doublebar Rabbitfish on 18% of dives.

Chance per dive in September across all sites here, from sightings in logged dives.

Also likely in September 394 species · chance per dive

Other months

Peak season: March, April, May.

All 23 dive sites in Koh Tao

More places to dive

Pair it, or trade up.

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Citizen science

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The ocean covers 70% of the planet but is the least-recorded place on Earth. Scientists can't be on every reef. Divers are.

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A mobula ray swimming in open blue water, a remora on its back
Mobula rayMobula sp.15 m · Princess Alice Bank, Azores
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