As we have these nice warm days at the moment it might be of interest to know some destinations where it is possible to fly to, jump out of the plane and go swimming. We are looking for these destinations, because we enjoy this and our labrador does so too.
In our area I do recommend:
Pontarlier (LFSB), short walk to a nearby lake
Deggendorf (EDMW) direct beside a lake, short walk to the river Donau
Vilshofen (EDMV) direct beside the river Donau
Juist (EDWJ) just a short walk to the beach, dogs are welcome on this part of the beach
What are your favorits?
For just a few hours at the beach Juist as well – absolutely!
Juist!
Kasos-South Aegean-Greece
https://www.you-fly.com/airport/lgks/Kasos#list
Helgoland
The answer must depend on how tough you are 
The UK is OK with a 4mm wetsuit… just about.
Croatia doesn’t get warm enough for me till possibly late summer.
Calvi, Corsica (EuroGA fly-in, Sep 2014) was great. A pity about the parking surface.
Greece (the Aegean) is the best place of course!
Peter wrote:
Croatia doesn’t get warm enough for me till possibly late summer.
It’s 31-35 OAT and 23+ water temperature (rising every day). I’ll check it tomorrow at Vis and let you know 
A favourite subject if mine, since I love summer swimming. Combining this with flying is of course fantastic.
So, assuming a may 5 minute walk from the airfield / strip (and leaving aside all the numerous airfields with swimming pools):
Castellon de la Plana
Massa-Cinquale
Caronia
Senegallia
Lido
Avio del Sole
Sant’Andrea Melendugno
Quiberon
Jastarnia
Visingsö
Vejrø
Quiberon
Granville
La Rochelle (little bit of walking)
Læsø (little bit of walking/Cycling)
L’Ile d’Yeu (little bit of walking or cycling)
L2K (little bit of walking/cycling) am I stretching it?
Lausanne & Geneva!
