It is billed as the last word in relaxation, with a “healing climate” and “soothing energies”.
So it was perhaps the ideal location for a final holiday for the Prime Minister before he leaves Downing Street, as well as a belated honeymoon.
Guests can dine on bear cheeks, bathe with vegan toiletries and sleep in rooms without WiFi. Their two children did not accompany them.
The Vila Planinka, where rooms range from £242 to £542 per night, is a five-star boutique hotel which promises guests they will “slow down, harmonising your rhythm with your inner balance”.
After the Johnsons left on Sunday evening, hotel owner Katja Batajelj and her daughter Lana told The Telegraph: “He was one of the most pleasant guests we have had and asked for nothing. He was enthusiastic about the food and drink. If all guests were like him we’d be very lucky.
“They were very active. They went hiking, they swam in the lake. They also went to Postojna caves and Boris was very enthusiastic about them. He said he never imagined anything like the caves existed. It was wonderful to have him in Slovenia.”
The hotel’s rooms have no electronic devices and no wiring in the walls, and Wi-Fi is only available in the lobby unless guests specifically request a connection in their room.
Its website claims that the locals discovered “four energy points” behind the site several centuries ago, which give it a “therapeutic effect”.
But the presence of the British Prime Minister and his wife caused some disturbance to the valley’s tranquility.
Residents said they were “very excited”. A billboard was erected outside of a house just a couple of minutes’ walk from the hotel with a picture of Mr Johnson holding a birthday cake superimposed on an image of the town with the message: “Cheerio old chap! Happy Birthday.”
It is unclear why they were sending Mr Johnson birthday wishes when he celebrated in June.
But the excitement may be attributable to the fact, revealed by a local hairdresser, that the most famous person they are used to seeing is Jan Plestenjak, a Slovenian pop star much less recognisable to an international audience.
During his stay Mr Johnson was spotted out cycling with his bodyguards, and he and his wife have also been seen visiting the nearby tourist hotspot of Lake Bled.
If the fresh mountain air gave them an appetite, the good news is that the hotel boasts a gourmet restaurant with such hearty fare as bear cheeks, lemon-soaked trout, agnolotti with fermented chestnuts, and bee pollen ice cream.
Bear meat is a delicacy in Slovenia, which has one of the highest densities of brown bears in the world.
Downing Street had wanted to keep the couple’s location under wraps for security reasons, but Robert Golob, the Slovenian prime minister, blew their cover on Friday by confirming the couple were in his country.
The couple arrived on Wednesday on a commercial flight and left on Sunday evening in preparation for Mr Johnson’s return to work in Downing Street on Monday.
The Jezersko region, on the border with Austria, is lyrically described by the local tourist board as part of “the green pearl of Europe” and is a favourite with hikers, climbers and mountain bikers.