PickADive Research
The Most Reliable Diving Months on Earth
Quick answer
August is historically the calmest diving month worldwide, with 75% of sampled site-days scoring favorable, against 65% in January and February. Cambodia and Indonesia have the most reliable diving year-round, favorable on 96% of days. These are multi-year conditions averages across 61 countries, not a forecast for any trip.
We analyzed multi-year conditions history across thousands of salt-water dive sites in 61 countries — the share of days each month that historically scored favorable for diving. Three findings stand out.
A favorable day is one where PickADive’s grade of the day’s peak wave height and peak wind — with recent rain as a turbidity signal — reaches the favorable band; each figure below is the share of such days in that month, averaged across a country’s salt-water sites.
Computed · methodology below · free to cite with a link to this page.
August
is the world’s calmest diving month — 75% of sampled site-days favorable, vs 65% in Jan–Feb.
Cambodia and Indonesia
have the most reliable marine diving measured: favorable 96% of days on the year, never below 86% in their worst month.
83 pts
is the biggest seasonal swing — Seychelles: 99% favorable in Mar, 16% in Jul. Booking month is everything.
The planet’s diving year
Averaged across every qualifying salt-water site on PickADive, the share of days historically favorable for diving, by month:
Northern-hemisphere summer wins globally — but the country tables below show the average hides everything that matters.
Which countries have the most reliable diving months?
Where conditions barely have an off-season. Southeast Asia’s sheltered seas dominate — with Canada’s fjord-protected Pacific coast the surprise of the dataset.
| # | Country | Favorable days, annual avg | Worst month |
|---|---|---|---|
| 1 | Cambodia | 96% | Sep (86%) |
| 2 | Indonesia | 96% | Jul (92%) |
| 3 | Canada | 95% | Dec (92%) |
| 4 | Philippines | 94% | Jul (85%) |
| 5 | Cuba | 93% | Dec (88%) |
| 6 | Malaysia | 93% | Jan (73%) |
| 7 | Cyprus | 92% | Mar (85%) |
| 8 | Thailand | 92% | Sep (83%) |
| 9 | United Arab Emirates | 92% | Feb (77%) |
| 10 | Croatia | 90% | Nov (83%) |
Where does the booking month matter most?
The widest gaps between best and worst month. Arrive in the wrong season at these destinations and you’re diving a different country.
| # | Country | Best | Worst | Swing |
|---|---|---|---|---|
| 1 | Seychelles | Mar (99%) | Jul (16%) | 83% pts |
| 2 | Federated States of Micronesia | Sep (94%) | Feb (11%) | 83% pts |
| 3 | Vietnam | May (95%) | Dec (20%) | 74% pts |
| 4 | Marshall Islands | Sep (82%) | Jan (8%) | 74% pts |
| 5 | Northern Mariana Islands | Jun (74%) | Feb (5%) | 69% pts |
| 6 | Portugal | Jul (76%) | Jan (7%) | 69% pts |
| 7 | Palau | Jun (95%) | Feb (28%) | 67% pts |
| 8 | Grenada | Sep (99%) | Feb (39%) | 60% pts |
| 9 | Curaçao | Oct (69%) | Jul (12%) | 56% pts |
| 10 | Cayman Islands | May (95%) | Dec (40%) | 55% pts |
The hardest-working coastlines
The lowest year-round favorable shares — open-ocean coasts where big seas are the norm. Not a list of bad diving: South Africa’s sardine run and cage diving are legendary because this water works so hard. These are the destinations where checking the forecast is non-negotiable.
| Country | Favorable days, annual avg | Best window |
|---|---|---|
| South Africa | 19% | Apr (26%) |
| Mauritius | 33% | Dec (54%) |
| Marshall Islands | 34% | Sep (82%) |
| Portugal | 34% | Jul (76%) |
| Mozambique | 35% | May (46%) |
| Northern Mariana Islands | 40% | Jun (74%) |
| Colombia | 41% | Oct (59%) |
| Bonaire | 43% | Sep (69%) |
All 61 countries, A–Z
| Country | Annual avg | Best month | Worst month | Swing |
|---|---|---|---|---|
| Australia | 47% | Jan (59%) | May (30%) | 28 |
| Bahamas | 84% | Jul (99%) | Dec (70%) | 29 |
| Belize | 79% | Sep (97%) | Jun (70%) | 27 |
| Bonaire | 43% | Sep (69%) | Jul (15%) | 54 |
| Brazil | 55% | Feb (63%) | Sep (42%) | 21 |
| British Virgin Islands | 63% | May (88%) | Feb (36%) | 52 |
| Cambodia | 96% | Apr (100%) | Sep (86%) | 14 |
| Canada | 95% | Jul (99%) | Dec (92%) | 7 |
| Cayman Islands | 64% | May (95%) | Dec (40%) | 55 |
| Colombia | 41% | Oct (59%) | Feb (27%) | 32 |
| Costa Rica | 65% | Mar (90%) | Jun (44%) | 46 |
| Croatia | 90% | Jun (98%) | Nov (83%) | 15 |
| Cuba | 93% | May (99%) | Dec (88%) | 11 |
| Curaçao | 44% | Oct (69%) | Jul (12%) | 56 |
| Cyprus | 92% | Jul (100%) | Mar (85%) | 15 |
| Dominica | 51% | Sep (84%) | Jul (30%) | 54 |
| Ecuador | 82% | Feb (93%) | Jun (69%) | 24 |
| Egypt | 81% | Jul (92%) | Feb (67%) | 25 |
| Federated States of Micronesia | 63% | Sep (94%) | Feb (11%) | 83 |
| Fiji | 68% | Jan (92%) | Sep (47%) | 46 |
| France | 59% | Jun (80%) | Jan (35%) | 45 |
| French Polynesia | 49% | Mar (69%) | Jun (34%) | 35 |
| Greece | 78% | Jun (89%) | Feb (64%) | 24 |
| Grenada | 67% | Sep (99%) | Feb (39%) | 60 |
| Honduras | 62% | Sep (93%) | May (45%) | 48 |
| India | 90% | Apr (100%) | Jul (67%) | 33 |
| Indonesia | 96% | Nov (98%) | Jul (92%) | 7 |
| Ireland | 47% | May (67%) | Dec (32%) | 36 |
| Italy | 84% | Jun (98%) | Jan (70%) | 29 |
| Japan | 54% | Aug (72%) | Dec (36%) | 36 |
| Malaysia | 93% | May (100%) | Jan (73%) | 27 |
| Maldives | 87% | Mar (99%) | May (69%) | 30 |
| Malta | 66% | Jun (90%) | Dec (45%) | 45 |
| Marshall Islands | 34% | Sep (82%) | Jan (8%) | 74 |
| Mauritius | 33% | Dec (54%) | Jun (11%) | 43 |
| Mexico | 85% | Jul (94%) | Jan (78%) | 16 |
| Mozambique | 35% | May (46%) | Mar (27%) | 19 |
| Myanmar | 87% | Apr (100%) | Jul (61%) | 39 |
| Northern Mariana Islands | 40% | Jun (74%) | Feb (5%) | 69 |
| Norway | 66% | Jul (83%) | Dec (50%) | 33 |
| Oman | 77% | Mar (96%) | Jul (44%) | 52 |
| Palau | 71% | Jun (95%) | Feb (28%) | 67 |
| Panama | 85% | Sep (96%) | Feb (69%) | 27 |
| Papua New Guinea | 89% | Jan (98%) | Aug (75%) | 23 |
| Philippines | 94% | Apr (99%) | Jul (85%) | 14 |
| Portugal | 34% | Jul (76%) | Jan (7%) | 69 |
| Saudi Arabia | 84% | Nov (96%) | Feb (76%) | 20 |
| Seychelles | 67% | Mar (99%) | Jul (16%) | 83 |
| Solomon Islands | 89% | Nov (98%) | Sep (77%) | 20 |
| South Africa | 19% | Apr (26%) | Jun (11%) | 15 |
| Spain | 71% | Jun (85%) | Jan (50%) | 35 |
| Sudan | 81% | Oct (97%) | Feb (66%) | 30 |
| Tanzania | 79% | Dec (98%) | Jul (51%) | 47 |
| Thailand | 92% | Apr (100%) | Sep (83%) | 17 |
| Turkey | 86% | Oct (95%) | Apr (81%) | 14 |
| Turks and Caicos Islands | 59% | May (82%) | Feb (41%) | 41 |
| United Arab Emirates | 92% | Sep (99%) | Feb (77%) | 23 |
| United Kingdom | 57% | May (79%) | Dec (33%) | 47 |
| United States | 70% | Jul (88%) | Jan (57%) | 31 |
| Vanuatu | 76% | Dec (89%) | Aug (63%) | 26 |
| Vietnam | 63% | May (95%) | Dec (20%) | 74 |
Famous destinations, compared
Countries hide their stars, so here are the destinations divers actually book, by the same measure. One caution the data teaches: calm water and animal season are not the same thing — Socorro’s famous winter season is its roughest water, and divers cross anyway for the mantas.
| Destination | Annual avg | Best month | Worst month |
|---|---|---|---|
| Komodo | 100% | Feb (100%) | Jan (99%) |
| Bunaken | 100% | Apr (100%) | Feb (98%) |
| Anilao | 100% | Mar (100%) | Sep (99%) |
| Raja Ampat | 99% | Mar (100%) | Jul (97%) |
| Sipadan | 99% | Feb (100%) | Sep (97%) |
| Lembeh Strait | 99% | May (100%) | Feb (98%) |
| Cozumel | 97% | Aug (100%) | Feb (94%) |
| Koh Tao | 93% | Apr (100%) | Nov (82%) |
| Malapascua | 92% | Jun (100%) | Feb (82%) |
| Amed & Tulamben | 90% | Nov (100%) | Jul (77%) |
| Sea of Cortez | 88% | Jul (95%) | Jan (75%) |
| Galápagos | 87% | Feb (97%) | Jun (76%) |
| Tubbataha | 82% | Apr (100%) | Jan (45%) |
| Nusa Penida | 81% | Nov (95%) | Jul (68%) |
| Similan Islands | 81% | Mar (99%) | Jul (42%) |
| Red Sea | 81% | Jul (90%) | Feb (68%) |
| Great Barrier Reef | 55% | Jan (78%) | May (22%) |
| Cocos Island | 51% | Mar (87%) | Oct (20%) |
| Socorro (Revillagigedo) | 30% | Jul (69%) | Mar (12%) |
Sea-state favorability only — marine-life seasons are a separate question (each destination page covers both). The Similan figure is the method validating itself: its July trough matches the park’s actual May–October closure.
Methodology
PickADive’s live outlooks grade every hour at 4,800+ dive sites against wave height, swell period, wind, wind direction relative to the shore, and daylight. This report uses the climatology form of that grade: for each historical day, the day’s peak wave height and peak wind — plus recent rain as a turbidity signal — are scored with neutral site defaults, using three years of Open-Meteo marine and weather reanalysis (tides are not part of this dataset). We took every salt-watersite with at least two sample years per month, computed each site’s monthly share of days scoring in the favorable band, averaged across sites per country and month, and required at least 8 qualifying sites and full 12-month coverage — leaving 61 countries. Freshwater sites (lakes, quarries, cenotes) are excluded: they grade on wind only and would flatter any country that has them. Numbers are climatology — historical patterns, not forecasts, and never a safety judgment about any specific day. Full data: every destination has a free month-by-month page.
Press & researchers: this data is free to cite with a link to this page. Questions or custom cuts: team@pickadive.com.
Cite, download or embed this data
Licensed CC BY 4.0 — reuse it with a link to this page. Deep-link to any country with #country-slug (for example #canada).
PickADive (2026-08-25). The Most Reliable Diving Months on Earth: favorable-day climatology for 61 countries. https://pickadive.com/research/most-reliable-diving-months
Numbers are climatology — historical patterns, not a forecast, and never a judgment about any specific day.