Shades

The coastal town of Kamena Vourla (about 150 km north of Athens) has a certain reputation as a thermal place of well being.

From the wikipedia link above:

'The famous springs became important around 1926 when the chemist Michail Pertesis discovered the exceptionally high radon concentration in the water, which was thought of as a great value for people's health. Nearly ten years later (1930s), the first hotels started to develop. After World War II, Kamena Vourla was transformed into a famous tourist attraction'.

However the status and importance of this hot spring seems to have changed. The main bathing building has gone defunct. Just google Kamena Vourla + hot spring to see the ruin.  Such as this:

'During my short trip to Kamena Vourla I visited the Ippokratis hydrotherapy which apparently was the "new" building. Things did not look that new and certainly needed some restoration.
But within a driving distance there are some small healing thermal waters nearby that locals are using- the Kallyntika and Koniavitis.
Those I can totally recommend. I loved it'. 

source

Or read this from the greektraveller:

'Only few people come at this side of the settlement [of Kamena Vourla]. A wonderful pine grove, filled with big poplar trees, sedges and plane- trees all stretching in the shade of the mountain Knimida. The slopes fall vertically drowned by vegetation mixed with innumerable caves and rocks full of holes. Around this grove spring are the ruins of the old baths: Hotel “Radion”,the Baths “Asclepius”, other old hotels, all now deserted and devastated with wonderful neoclassical architecture and paint which has peeled away from the once glorious era: purple, ochre, sepia, warm yellow and shades of charcoal gray'.

Radion refers to it's radioactive waters: the hot spring of Kamena Vourla is one of the two hot springs of Greece known for their radioactive qualities (source). 

There are though a number of hotels with hot spring features (source). However, oddly the thermal connection is not a heavily used card: probably the most prominent Galini Wellness Spa & Resort hardly mentions their thermal pool.

Trashy
But besides what appears the main claim to fame, the town of Kamena Vourla has another few gems of hot springs, surprisingly underdeveloped. All the better.

An early morning this May sees me heading out north of town, along the many restaurants and cafes straddling the tiny beach where one can enjoy the view over the Gulf of Maliakos Kolpos towards the island of Evia and the Greek Peninsula to the north. 

On the roundabout just before the motorway there's a tiny sign in Greek (Πηγή Κουνιαβίτη or Koniavitis hot spring) pointing the way: head under the motorway without using the on ramp.

Coming onto this small lane, it just fits between the no-mans land between motorway and mountain face. After a kilometer or so you'll hit a set of hot springs, though maybe warmish is a better description.

In all behind a twin number of changing cubicles / huts to take refuge from the sun/rain, there are 4 cement lined pools (see blog leading photo). Three of these see little use apparently (some scum / algae on top), but enthusiastic soakers are dipping in the last, which also seems to the warmest of the quadruple. All pools would appear to contain waters with temps from 32-34C.

As common on our Greek sojourn, we are called over to soak and enjoy. 

However we skip this, soakers have quite a choice here: just further up the road is another hot spring, which I'll cover later in this blog.

There's not much other info on soaking itself here, certainly not in English. I did find this experience:

'I'm not sure exactly what we were expecting, but we were surprised to find that after a 4 km walk the hot springs were actually cement pools in the middle of a trash heap right on the highway (and they smelled like sulfur). Even though at first all we could do was laugh, once we all got in and started to relax it was actually really really nice. The water was oily and made our skin and hair feel amazing'.