Thermopylae Hot Springs

Thermopylae means hot gates, and the springs that gave the battlefield its name still run right across the road from the Leonidas monument. You park on open ground, follow the road past an abandoned petrol station, and find a warm, milky, sulphur-scented stream about 40 to 42 C dropping over a small waterfall into rough pools beside old bath buildings. Sitting under the fall feels like a natural massage jet; the source, a short walk upstream, is hotter.

There is no fee, no gate and no staff, so it works as a free stop on the drive between Athens and Meteora, Pelion or Thessaloniki, and you can add the battlefield museum nearby. Bring old dark swimwear, because the sulphur and algae can stain it green, and pack water to rinse off since there are no showers. Entry points are slippery, with makeshift steps.

The honest downside: the site is scruffy, can smell strongly, and has a reputation for car break-ins, so leave nothing visible in your vehicle and keep soaks short.