Domogled-Valea Cernei
Romania's largest national park and its oldest reserve — a limestone corridor of thermal springs, Banat black pine and some fifteen hundred kinds of butterfly.
Protection here predates Retezat. In 1932 the Council of Ministers declared the whole Domogled forest a monument of nature — nine hundred hectares on the pyramid above Băile Herculane — which makes it the oldest nature reserve in Romania, three years older than the country's first national park. The park that grew out of it is now the largest of the thirteen at 61,211 hectares, running up the Cerna from the Danube end of the Banat through the Mehedinți, Cernei and Godeanu mountains, with Paltina at 2,070 metres the high ground and the Cerna itself, eighty-four kilometres from source to Danube, as its spine.
The rock is limestone and it is thoroughly hollowed: something like nine hundred caves, the gorges at Corcoaia squeezing to a few metres between walls over a hundred high, and the Vânturătoarea waterfall dropping about fifty metres in two steps, one of them a single forty-metre fall. But the Cerna's real peculiarity is heat. Sixteen thermomineral springs surface along four kilometres of the valley at Herculane, running from 38 to 62 degrees, some of them heavily sulphurous — and the same geothermal plumbing produces something rarer still. In the hillside above the resort, Peștera lui Adam and the Grota cu Aburi hold air at 35 to 45 degrees and support a cave fauna with a tropical microclimate, which exists nowhere else in Romania and almost nowhere in Europe. The valley's emblematic tree grows on the cliffs between: Pinus nigra subspecies banatica, the Banat black pine, some ninety per cent of whose world range is this corridor. On the ground below it live roughly fifteen hundred species of Lepidoptera — about forty-five per cent of everything that flies in Romania — which makes Domogled one of the richest butterfly localities on the continent.
The human record runs just as deep and is in worse repair. The Romans were bathing here by AD 153, at Ad Aquas Herculi Sacras, and left votive altars to Hercules; the Habsburgs revived the place from 1736 and built it into the spa that Franz Joseph called the most beautiful on the continent. The Neptune Baths, put up between 1883 and 1886 to Alpár Ignác's design — four thousand square metres, sixty-three private bathing rooms, four communal pools — were abandoned after 1989 and have been collapsing since, roof and walls in 2019, more of the upper floor in December 2021. Europa Nostra listed the building among Europe's seven most endangered sites in 2022, and a volunteer outfit called the Herculane Project has been consolidating masonry and roof trusses since 2017. Further up the valley the losses are of a different kind: the Cerna–Motru–Tismana hydro scheme, begun in 1972, put a 110-metre rockfill dam across the river at Valea lui Iovan and drowned the old valley behind it.
What's worth knowing before you go
Băile Herculane is the gateway and there is no real alternative. It sits on CFR line 900 between Bucharest and Timișoara and every passenger train stops; the station is a few kilometres downstream of the historic centre. The resort is about five kilometres off the DN6/E70. For the upper Cerna, the approaches are the DN67D up the valley or the DJ608 through Cornereva.
This is the lowest and most Mediterranean of the Romanian parks — Herculane sits at around 160 metres — so Domogled itself is walkable through most of the year, though the ascent from the resort by the Poteca Pisicii is steep, exposed and on unstable scree, and is explicitly not a winter route. The high Godeanu ground behind is a different mountain and holds snow into June. Come between May and July if the butterflies are the point. And when you have finished photographing the Roman baths, walk up to the steam caves above them: the natural version of the same water, forty-five degrees in the dark, with its own endemic fauna.