The answer to the title is the Canary Islands. I say “only politically” because technically the islands are actually in North Africa but Spanish territory. Nevertheless, for a relatively short flight from Europe, these islands offer the best opportunity for Vitamin D in winter months.
We opted for Tenerife among all the Canary Islands because of the various activities it offers for young children. Temperatures reaching high 20C during the day in February, sunshine and clear blue skies were exactly what we needed coming from the cold and rainy Northern Europe. Even the ocean’s temperature was bearable at times for kids to splash around. Nonetheless, the beautiful sandy beaches that the southern part of the island offers give hours of entertainment for children anyway.
Tenerife certainly lacks the beauty and sophistication of other Spanish islands like Mallorca and yet it is also popular among German, Russian and British tourists because of its mild winter weather in the south. The norther half of the island is a different story. North of the volcanic national park of El Teide is often chilly, foggy and rainy. The two halves of the island experience completely different climates. It is also noticeable in the nature. Whilst the north is very green, the south is pretty much a desert.
Whilst the island lacks historical and architectural charm, there are still surprisingly nice towns and districts, which are UNESCO World Heritage sites and they can be a nice activity such as La Orotava in the north of the island, the cute pretty villages of Vilaflor, Garachico and Masca near the El Teide National Park and the historical centre of San Cristobal de la Laguna near the capital of the island Santa Cruz.
If you are into nature and hiking, besides the main attraction of the island, which is El Teide Volcanic National Park, the rural park of Anaga, Sendero El Bosque Encantado and the cliffs of Los Gigantes are highly recommended.
As for families with young children, activities are plenty; such as the Monkey Park in Los Cristianos where guinea pigs are more than ants, submarine safaris and whale watching tours in the ocean. There are waterparks and very famous zoos but as a principle, we are opposed to animals being in such enclosures so we do not visit them nor would recommend them. There is also a light and music fountain in Playa de las Americas, which the children find quite entertaining. I have to add there that Playa de las Americas in Arona gives a mini Las Vegas vibe.