The thermal water, explained

Beneath the peninsula is geothermal water, and it surfaces most notably at Ilıca — the name simply means hot spring. In places it emerges directly into the shallows of the bay, which is why the sea there warms earlier in the season than elsewhere on the coast.

The practical form this takes today is thermal pools and spa facilities attached to hotels along the Ilıca shoreline, alongside a small number of public and municipal baths. Waters are mineral-rich and warm; the traditional local use is soaking rather than swimming, in short sessions.

This is also what gives Çeşme a genuine off-season. When the beach clubs close in late October, the thermal hotels keep operating through the winter, and the town keeps a quiet weekend trade based on the water rather than the sea.

A few practical points. Sessions are usually timed rather than open-ended, hot mineral water is dehydrating, and anyone with cardiovascular conditions or who is pregnant should take medical advice before using hot pools. Facilities vary widely in style — from clinical to resort — so it is worth asking what a given hotel actually offers before booking a stay around it.

If you are visiting in summer and curious rather than committed, the simplest version is a morning swim at Ilıca beach where the warm water reaches the shallows, which costs nothing and requires no booking.