Kashiwajima's Most Popular Month Has the Worst Visibility
2026-03-16
Kashiwajima in Kochi is Japan's 'macro paradise.' Of 1,499 observations, May dominates with 249 — confirming Golden Week through early summer as peak diving season. But visibility data reveals this isn't actually the best time for clarity.
Monthly Data Overview
| Metric | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Vis | 16.8 | 15.1 | 11.6 | 10.5 | 11 | 11.9 | 13 | 13.6 | 14 | 12.9 | 14.2 | 16.7 |
| Temp | 18.1℃ | 16.6℃ | 17℃ | 18.4℃ | 19.7℃ | 22℃ | 24.8℃ | 25.7℃ | 25.8℃ | 25.2℃ | 22.7℃ | 19.8℃ |
| Obs | 93 | 54 | 89 | 120 | 249 | 223 | 164 | 81 | 82 | 142 | 97 | 150 |
Three Truths from the Data
1. May Is Popular but Not the Clearest
May's 11.0m is the third-lowest month. GW holidays drive the most divers, but spring bloom still lingers. For visibility-focused diving, January (16.8m) or December (16.7m) is far superior.
2. Winter Kashiwajima Is Another World: Jan 16.8m
January's 16.8m is 1.6x April's 10.5m. The Kuroshio approaches closest in winter, reducing plankton. Water is 18.1°C (drysuit recommended), but for macro photography in clear water, winter is unbeatable.
3. Autumn Is the True Sweet Spot
September offers 14.0m visibility with 25.8°C water — the best 'clarity + comfort' balance. November is also strong (14.2m / 22.7°C). Autumn means fewer crowds and better conditions.
About the Data
1,499 observations at Kashiwajima (2006–Mar 2026). May (249) and June (223) dominate, reflecting peak macro diving season.
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