Chaweng Reef
Chaweng Reef is a dive site in Koh Samui, Thailand. The sea floor at the site position lies at about 20 meters. Currents typically run at 0.5 km/h and reach 1 km/h on the strongest days. Water temperatures range from 29°C in January to 32°C in May. The typical daily tidal range is about 1.0 m. Species recorded in the area include Dorippoides facchino, Doublebar Rabbitfish, Longfin Bannerfish, Arabian Cowrie and Almond Ark.
Dive Conditions
Data sources: currents and water temperature from Open-Meteo Marine (CC BY 4.0), hourly model values 2024; seabed depth from the GEBCO 2020 Grid, sampled at the site coordinates (grid resolution about 450 m). Tidal range is the median daily range of modelled sea level from Open-Meteo Marine, hourly values 2024. Species observations from iNaturalist, checked against the World Register of Marine Species.
Conditions at Chaweng Reef through the year
Sea surface temperature at the site coordinates, averaged per month from hourly model values for 2024. The water is warmest in May at about 32 °C and coolest in January at about 29 °C, a spread of 3.3 degrees across the year.
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 28.6 | 28.9 | 29.5 | 31.2 | 31.9 | 31.1 | 30.7 | 30.7 | 30.3 | 30.5 | 29.7 | 28.7 |
Ocean current at the site runs at a typical 0.5 km/h. In the strongest tenth of the hours modelled for 2024 it reaches 1.0 km/h, which is when entries are normally timed to slack water at the turn of the tide.
The tide moves the water level by a median 1.0 m over a day, and by up to 1.3 m on the largest days of the month. That range drives how much water is exchanged over the reef and when the current turns.
In the open sea off Chaweng Reef, the highest wave of the day exceeded 1.5 m on 0.2 % of days between 2015 and 2024. The roughest month was January (1 % of days), the calmest March (0 %).
| Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|
| 1 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 0 | 1 |
The seabed directly under the site coordinates sits at about 20 m. This is a bathymetry grid value with a cell size of roughly 450 m, so it describes the depth of the area rather than the deepest point a dive can reach.
How Chaweng Reef compares
These comparisons use only the measured values above, set against the 376 dive sites published on findadive.com. A percentage shows the share of other sites with a lower (or higher) value, so it reads the same way wherever the site is. Chaweng Reef sits with its mean water temperature in the top tenth and its typical current in the bottom tenth of all listed sites.
| Measure | This site | Compared with all sites | Median in Thailand |
|---|---|---|---|
| Mean water temperature | 30.1 °C | warmer than 100 % of the other 375 sites | 29.7 °C (126 sites) |
| Water temperature in the coolest month | 28.6 °C | warmer than 68 % of the other 375 sites | 28.7 °C (126 sites) |
| Typical current | 0.5 km/h | weaker than 97 % of the other 375 sites | 0.7 km/h (126 sites) |
| Current in the strongest 10 % of hours | 1.0 km/h | weaker than 97 % of the other 375 sites | 1.3 km/h (126 sites) |
| Median daily tidal range | 1.0 m | smaller than 94 % of the other 375 sites | 1.6 m (126 sites) |
Water temperature, current and tide from Open-Meteo Marine (CC BY 4.0), hourly model values for 2024 at 9.5161°, 100.0685°. Seabed depth from the GEBCO 2020 Grid. Wave statistics from ERA5-Ocean via Open-Meteo Marine (contains modified Copernicus Climate Change Service information 2015–2024), daily maximum wave height on a 0.5° grid; land shelter tested against Natural Earth coastlines.
Marine life recorded at this site
Research-grade observations from iNaturalist within about 12 km of these coordinates.
