Primal soaking

The areas of land along the stretches of water between mainland Greece and the northern part of Evia island (let's say North Euboean Gulf / Malian Gulf) host quite a few hot springs. Some are lesser known and others (such as Aidipsos) attracting quite some fame (and fortune to the tourism sector).

However the prime soak of this area is yet to be highlighted here. 

The village of Thermopylae translates as hot gates and may well have been the entrance to the caves of Hades, God of the underworld and thus of the souls of the Dead.

Though the hot spring gives the village this awe inspiring name, it's the terrain around Thermopylae what has brought the village more fame. 
The single lane village now lies quite some distance from sea, as the shore line progresses seawards each year due to sedimentation. But back more than 2000 years ago, there was little land between the Gulf of Malia and the Kallidromo mountains. This gave the area huge strategic significance, and Thermopylae has borne witness to a number of battles, none the more significant than the Battle of ... Thermopylae. 
The Battle witnessed a Persian army held up for quite some time by a relative small number of Greeks and is nowadays remembered as a heroic fight of nationalism against the invader(s). 
Today there's a large museum remembering this battle and a statue of Leonidas to admire, the hero leader the defence.

Visitors to both can wander around the surrounding plains and discover that along the base of the mountain, flows a stream which reeks of sulphur. Follow this and one comes to a man-made waterfall, pictured below. 

Sometimes referred to as Loutra Thermopilon / Loutra Thermopylon, this is also the focal point for thermal tourists who frolic in both the waterfall itself as well as the canal above and stream below.

Refuge

Further away are what have been bathing buildings. But now these were slightly overrun and function as  a center for recent (?) refugees.

Let's look at the history of the hot springs development. Oddly enough this comes from the Japan Times (Apr. 11, 2014):

'To the uninitiated, the site appears inauspicious, close to an abandoned gas station and a derelict hotel. Bathers change in their car and step over a wobbly wooden pallet to reach the springs.

“We have an exceptional product, but it is poorly used,” sighed Markos Danas, secretary general of the union of Greek spa towns. He notes that across the country, fewer than a dozen sites offer acceptable tourism infrastructure. “Hot springs are mostly run by local communities, and this has limited the scope of development,” he said.

...

The spa towns are now hoping an EU directive that authorizes reimbursing citizens taking hot baths in other member states will revive interest. Greece’s state privatization agency last year also offered four hot springs in central Greece, including Thermopylae, for sale to private developers.

But there were no takers — meaning more free visits for Kyriazis and his fellow bathers in the foreseeable future'.

But as said, the buildings now house refugees. On this, Al Jazeera (Jul. 16, 2016) notes:

'Thermopylae, Greece - Akram al-Majidi lifted his left arm to show the skin disfigured by severe burns after a car bomb exploded outside his shop in Baghdad in 2008.
The flesh, once on the outside of his forearm, was pushed to the other side, leaving just a thin layer of scorched skin on top of his radial bone.
Akram, 34, says his life was simple in Iraq. He owned a bakery, preparing special cakes for weddings, birthdays and other occasions.
"I'm left-handed. I wrote, ate, made cakes - all with my left hand," Akram tells Al Jazeera in his family's tiny room in a bankrupt and deserted hotel converted into a refugee camp for hundreds of people in Thermopylae, central Greece'.

Apparently since a few years, the pre-WWII (1935, source) bathing establishment has closed and was awaiting new (private / foreign) investment. And in the meantime functioning as a refugee camp. 

It could be much worse, but there certainly seems to be quite some overpopulation and the distances from a proper supermarket are considerable. So lots of boredom for the refugees, waiting for what the future will bring. 

A positive mention is that they were not impeding on the soaks themselves, thus the hot stream was available for tourist.

Sourced
As it was quite busy at the falls themselves, we decided to hike a bit further upstream to seek the soaking source, solitude and solace. Only 150-200m further there's a quiet pool which forms the source of the stream. 
Strip and soak. 
For a hot day it was certainly a hot soak. I note a temperature of 40°C
(source). 

Though it felt hotter. Witness this sign saying it's 42°C ...:

And it may cause heart problems.

A  photo of the source pool: 

 

Pits
Some practicalities. 
Getting here is not too difficult: north of the village, pass the museum on your right and before the defunct petrol station turn left down a dirt road for the 200 meters or so that it lasts.
Directly adjacent to the waterfall is a shop slash snack bar . 

From the internet there's not too much to add. There are great photo's from roughly 5 years back, here and here.

 

Tripadvisor is not over-impressed by the soaking possibilities: it's no. 4 of the 4 things to do in Thermopylae (link), fours stars though. One review: 

'The natural hot springs provides a great pit stop if you are travelling with kids from Athens to Pelion or Meteora. This hidden gem has very few visitors and is free. Sitting under the hot waterfall provide you with a natural jacuzzi that any kids (and adults as well) would love. Combining it with a small history lesson for the kids in the nearby monument for the battlefield of Thermoplastic complete the experience. Highly recommended site.
Please note: this is a natural site. There are no bathroom or change room facilities'.

Marginally better the same review site under the name of Loutra Thermopilon puts the hot springs at no. 15 (out of 19) of things to do in the Phthiotis region (link).
 

There's this:

'The thermal springs of Thermopylae were already known in the ancient times and they are placed at 15 km south of Lamia, in the centre of Greece. A large flow of water is received and the rare phenomenon of a thermal waterfall is constituted. The therapeutic indications of this particular place are rheumatic conditions, arthritis, neurological and gynaecological disorders, diseases of the respiratory system, asthma, bronchitis and pulmonary emphysema'.

Finally, not always can we expect good news at natural soaking sites. Especially in a poor secure site near motorway access, though that's no excuse.  There are reports of seediness, as a policeman (!) is arrested for voyeurism (Newsbomb.gr, Nov. 6. 2015) while earlier last year there are complaints of loads of rubbish (Aftodioikisi.gr, 15 Jan. 2015).