When To Go · Destination Guide
Cold-water wrecks, kelp reefs and Atlantic wildlife across Cornwall's two coasts
When to go
The most dependable allactivity window is May to September, when water is warming, daylight is long, local boat and training schedules are strongest, and topside services are fully active.
Best overall window
Longer daylight, broad operator availability, and water warming toward about 16°C by July to September. Summer remains weatherdependent.
Outside that window
Specialist coldwater period. Water can approach 7°C in late winter, while storms, swell, short daylight, and reduced schedules constrain plans.
Start with the overall answer, then switch only when scuba, freedive, snorkel, or topside timing changes the trip in a meaningful way.
The overall row stays visible so you can compare it against the currently selected scope.
| Scope | Jan | Feb | Mar | Apr | May | Jun | Jul | Aug | Sep | Oct | Nov | Dec |
|---|---|---|---|---|---|---|---|---|---|---|---|---|
| Overall | Overall - Jan: Tradeoffs | Overall - Feb: Tradeoffs | Overall - Mar: Tradeoffs | Overall - Apr: Good | Overall - May: Best | Overall - Jun: Best | Overall - Jul: Best | Overall - Aug: Best | Overall - Sep: Best | Overall - Oct: Good | Overall - Nov: Tradeoffs | Overall - Dec: Tradeoffs |
These regional shifts apply only to the selected scope.
| Area | Best months | Why it changes |
|---|---|---|
| Falmouth and the east side of the Lizard | May to October | This coast generally provides the longer, more sheltered planning window, but easterly weather, tidal reefs, and harbour activity still control individual sites. Main caution: Same-day route swaps become more likely when weather builds. |
| Newquay and the Atlantic north coast | June to September, with flat-sea flexibility | The Atlantic coast has a narrower usable window. Main caution: Crossings and exposed sites can feel rougher in this stretch. |
These do not replace the overall planner. Use them only if a specific animal or event is driving your trip dates.
Blue Shark Season
Best for Freedive, Snorkel
May to Oct
Specialist operators report blue sharks in Cornish waters from May through October.
Basking Shark Possibility
Best for Scuba, Freedive, Snorkel, Topside
May to Sep
Broad Cornwall dive guidance reports summer basking shark sightings.
Grey Seals
Best for Scuba, Freedive, Snorkel, Topside
Year-round
Seals are reported around both Porthkerris and Newquay.
Spring Thornback Rays
Best for Scuba
Mar to May
Cornwall dive guidance highlights spring as a useful period for thornback ray sightings around southern sites.
Winter Diving Seabirds
Best for Topside
Nov to Mar
The Falmouth Bay to St Austell Bay Special Protection Area supports overwintering blackthroated divers, great northern divers, and Slavonian grebes, adding a strong binocularsandcoastwalk theme to colder trips.
Built from climate references, access rules, and destination operators. Wildlife timing and route flexibility can shift year to year.