Master Divers — Koh Tao Weekly Dive Report
Period: Monday 17.11 – Sunday 23.11
Location: Koh Tao, Gulf of Thailand
This week in Koh Tao we’re expecting some pretty heavy weather coming in. Winds will build through the week, bringing increasing swell and more active surface conditions. Rain showers will be intermittent but more likely from mid-week onward. Morning dives may remain the most favorable, especially early in the week, while afternoons could become rougher and less predictable.
Continue reading to get the detailed version of the Koh Tao Weekly Dive Report
☔ Rain
- Rain is expected to be relatively light at the start of the week, with scattered showers more likely than steady downpours.
- From Wednesday onward, the risk of more frequent or heavier showers increases as model guidance shows stronger wind flow and moisture convergence.
- For diving, this means planning for possible wet afternoons, especially later in the week.
💨 Wind
- Monday 17 Nov: Wind speeds are expected to be low to moderate, around 9–11 kts in the early hours
- Mid-week (19–20 Nov): Winds are forecast to pick up significantly, showing gusts reaching 25–28+ kts by Thursday.
- Direction: Predominantly NE to E-NE, which could make the eastern side of Koh Tao more exposed to wind-driven chop.
🌊 Swell & Waves
- Early in the week wave heights are relatively moderate (~0.8–1.0 m), with short wave periods.
- As wind strengthens mid-week, swell builds with swell heights rising to ~2.5–2.6 m around Wednesday / Thursday during peak wind times
- This increase in swell and wave period suggests potential surge and rougher surface water, especially on more exposed dive sites.
🌙 Tides & Currents
- Although specific hour-by-hour tide data for the week would come from a dedicated tide chart, strong winds and swell later in the week could generate stronger surface current or surge.
- Dive planning should favor protected sites or deeper entries later in the week, especially if surface riding gets rough.
👁️ Underwater Visibility
- Given the mixed forecast, visibility early in the week is likely to be the best — calmer wind, lower swell, and less rain should help.
- As conditions become rougher mid to late week (with more swell and rain), visibility may drop due to sediment stirred up by surge and runoff from rain.
- For safety and quality, morning dives early in the week are likely to give you the best clarity, while afternoons might be less predictable.
- Unfortunately there is also some algae bloom happening, so some green is expected.
As always, at Master Divers we pick our dive sites on a day-to-day basis, to ensure the best conditions possible for all dives. Expect sheltered sites and coves especially from mid-week and onwards.
🐠 Marine Life Highlights
Slower dives will be very rewarding: with somewhat variable visibility, you’ll want to look closely for macro life like nudibranchs, shrimps, and hermit crabs hiding in nooks of the reef. And if the currents pick up mid-week, there’s a shot at spotting larger visitors.As always, we will probably see our usual suspects such as pufferfish, blue-spotted stingrays, or barracudas cruising in stronger water flow.
Recommendations for Divers
- Wetsuit: Water temperature stays warm (typical November), so a 3 mm shorty or rashie will be sufficient, unless you are prone to being cold in which a 3mm full wetsuit should be fine
- Best Dive Strategy:
- Early Week Mornings: Ideal for calmer conditions and somewhat better visibility.
- Mid-to-Late Week: Pick sheltered dive sites, or go for deeper dives to avoid strong surface movement.
- Early Week Mornings: Ideal for calmer conditions and somewhat better visibility.
- Safety:
- Monitor surface condition continuously.
- Listen to your dive guide / boat crew — transferring in stronger wind or swell may be tricky.
- Dive conservatively and within your limits as conditions may be subject to change..
Dive safe and see you underwater!
