The August crowds are leaving, the water stays warm for weeks. This is the moment the southern Spanish coast opens up the way it looks in photographs - with no queue for parking and no towel-to-towel packing.

The strongest example is Bolonia near Tarifa, where you swim beside the Roman ruins of Baelo Claudia. The beach has a dune 30 metres high and 200 wide, slowly swallowing the pine forest behind it. The archaeological site holds remains of a forum, temples, a sanctuary, a market, a basilica, a theatre, baths and a fish-salting factory. Few places in the Mediterranean offer a swim and an ancient town in the same frame.

A few kilometres on is Punta Paloma, ten kilometres from Tarifa, where the dune landscape stretches for kilometres along the coast. It is a favourite of kitesurfers because of the wind that blows here almost constantly - the same wind that empties the other beaches and fills this one.

If you want postcard-coloured water, Maro near Nerja is the stretch of rocks and small coves with fewer people than the neighbouring beaches in the same municipality. With a mask or a kayak you can reach hidden waterfalls beneath the cliffs.

The hardest to reach is Cala de Enmedio in Cabo de Gata. It is half an hour on foot from Agua Amarga or twenty minutes from Cala Plomo - or you arrive by boat. There was once a coral reef here; what remains are fossilised dunes with small pools of intensely blue water forming between them.

In the same park is Playa de los Genoveses, a bay more than a kilometre long with shallow water and not a single facility. No shower, no bar, no shade. Whoever goes there brings water, food and sun protection - or comes back earlier than planned.

On the Atlantic side is El Palmar near Vejer de la Frontera: eleven kilometres of sand and water that actually cools you down, unlike the Mediterranean in August. There are plenty of beach bars and sunsets that need no filter.

In Huelva, Mazagon and Matalascanas rest on something rarely found - the Donana National Park at their back. The beaches are so long it is hard to end up near anybody. The sixteenth-century tower at Torre del Loro and the La Higuera tower, constantly washed by the sea, are the two most photographed points on that coast.

Near Marbella, Cabopino proves that even the most built-up coast in Spain kept something natural: fourteen kilometres from the centre, in the protected area of the Artola dunes, with a 15-metre Arab watchtower. And in Granada, La Rijana is a pebble beach ringed by rocks, where you rent a board or a kayak and go around the caves.

Ten beaches, not one of them requiring a plane ticket across an ocean. The question is whether the Balkans will ever learn that September is the best month at the sea - or whether we will all keep shoving into the first half of August because that is how it was last year too.