ROADBOOK

Roadbook S1 Borderless Trail — the course, trail by trail

36 km from PortoPiccolo along the Karst ridge: every CAI trail and every connecting section of the race, in the order you come to them.

The S1 Borderless Trail starts at PortoPiccolo and returns there after about 36 km, with Monte Ermada and the CAI 003 ridge at the heart of the course. This page describes the course in the order you run it: the CAI trails, the other routes that share stretches of it, and the race’s own connecting sections.

From PortoPiccolo to the Sentiero Rilke

The start from the Bora Village at PortoPiccolo is a breathtaking sight: the Adriatic all around, the white cliffs of the Karst escarpment above the bay. The race gets off to a fast start at ‘Le botteghe’, inside PortoPiccolo, and the course drops down Strada della baia and Strada di PortoPiccolo to Sistiana Bay; from the bay a flight of stairs climbs up to the road, and the S.P. 3, on tarmac, leads to Piazza Barone Goffredo de Banfield, where the course joins the Sentiero Rilke. It is about 2.1 km, almost all on road: the field has time to spread out before reaching the trail.

From here the course follows CAI 001, partly shared with the Alpe Adria Trail and, along the cliffs, with the Sentiero Rilke. These are separate routes that happen to run on the same ground here: sharing a stretch does not make them the same thing.

The Sentiero Rilke runs for just over two kilometres, suspended between sky and sea, along the Duino Cliffs Nature Reserve, between Sistiana/Sesljan and Duino/Devin. It was here, in the winter of 1912, that Rainer Maria Rilke — a guest of Princess Marie von Thurn und Taxis at Duino Castle — heard the first words of the Duino Elegies carried to him on the wind: ‘Who, if I cried out, would hear me among the hierarchies of angels?’ It is from these cliffs, too, that the Corsa della Bora takes its motto: ‘Being here is glorious’.

Duino and the Sentiero del Mitreo

The course follows the Sentiero Rilke as far as Duino/Devin and passes through the old village in front of Duino Castle, the residence of the princes of Thurn und Taxis, where, according to tradition, Dante was a guest before Rilke; beside the ruins of the old castle you can make out the White Lady, the rock shaped like a veiled woman.

From Duino the course picks up CAI 001a — Sentiero del Mitreo. At the Mithraeum Cave, also known as the Duino Mithraeum, it leaves CAI 001a for CAI 033. Shortly afterwards comes the second point where the races split: the S1 Family Hike & Trail turns off onto its own shorter loop, while the S1 Half Trail, S1 Borderless Trail, S1 TransKarst Ultra and S1 Bora Ultra carry on along CAI 033.

Towards Medeazza

Past Duino the terrain changes character: you leave the coastal cliffs behind and head onto the plateau, where Monte Ermada — Grmada in Slovenian, 323 metres — dominates the landscape like a sentinel between two worlds. The climb is gentle and steady through mixed woods of pine and beech; the mountain’s slopes still hide trenches and fortifications from the Great War.

The course stays on CAI 033 and then switches to CAI 003a, which leads to Medeazza/Medja vas, a village of stone houses where the Italian Karst looks out towards Slovenia. Here, at around km 10.2, comes the major race split: the S1 TransKarst Ultra and S1 Bora Ultra head off on the long branch towards Jamiano, while the S1 Borderless Trail stays with the S1 Half Trail and bears towards Monte Ermada.

The cross-border sector of Monte Ermada

From Medeazza the course picks up CAI 003 — Alta Via del Carso — and runs through the cross-border sector of Monte Ermada/Grmada, past the area around the Jastreb summit, the Grofova jama (Grotta del Fuoco, also known as Vogenca) and the Grotta 1ª a nord del Monte Querceto.

After the Sixth Battle of the Isonzo in 1916, the Austro-Hungarians, having fallen back from the heights around Monfalcone, turned Ermada into the defensive linchpin that controlled the Brestovizza valley and the routes towards Trieste. Today the mountain is an open-air museum — trenches, cave shelters, artillery emplacements and observation posts — and a stop on the Walk of Peace/Pot miru, the cross-border remembrance trail linking more than three hundred First World War sites across Italy and Slovenia, from the Alps to the Adriatic; the Walk of Peace documents the mountain’s positions and hiking loops. The Grofova jama is a cave rich in formations, where Austro-Hungarian engineers carved out terraces and bunks for the troops.

The Grotta del Motore, where the Borderless carries on

The course reaches the Grotta del Motore, also known as the Caverna del Monte Querceto. This is where it parts company with the S1 Half Trail, at around km 13.3: the Half leaves CAI 003 to climb to the top of Ermada, while the S1 Borderless Trail carries on east along CAI 003.

The route passes close to the Grotta Dörfler, where the natural part of the cave opens into a tunnel dug during the First World War to link two dolines and shelter the troops. It then goes past Monte Sambuco/Bezgonov vrh and, straight afterwards, at around km 15.9, rejoins the S1 TransKarst Ultra and S1 Bora Ultra, sharing their return leg.

The shared return leg: Precenico, San Pelagio and Lupinc Park

From the point where the routes rejoin, the course follows CAI 003 as far as CAI 032, which leads through the Precenico area to San Pelagio/Šempolaj. Between San Pelagio, Prepotto/Praprot and the Fornace di Aurisina, the route strings together local connecting sections, a short stretch of CAI 010, the non-CAI section through Lupinc Park, a stretch of CAI 035 and a connecting section near the Fornace and the SP 5, before picking up CAI 010 again towards Santa Croce/Križ. CAI 010 should not be called the Sentiero Gemina: in the CAI register, the Sentiero Gemina is CAI 042.

The Lupinc Great War Park is an open-air museum created by Danilo Lupinc on his own land for the centenary of the First World War: trenches dug into the limestone by Russian prisoners of war in the service of the Austro-Hungarian army, a plaque dedicated to his grandfather Anton Terčon, who fell in 1916, and the Grotta Lesa, a natural doline with a collapsed roof reached through a stone arch.

Santa Croce and the finale by the sea

After Lupinc Park the course drops towards the sea, with the horizon opening wide over the Adriatic, all the way to Santa Croce/Križ — once a village of Slovenian fishermen, who climbed up from the coast along the Sentiero della Salvia to watch for shoals of tuna in the Gulf of Trieste/Tržaški zaliv. From here on, the closing section is the most runnable of the entire race.

From Santa Croce the course follows stretches of CAI 001 and connecting coastal paths and nature trails, then short sections of CAI 023 — Sentiero Tiziana Weiss, named after the Trieste climber who died in 1978, aged 26, on the Pale di San Martino. The path runs level, high above the sea, to the Vedetta Weiss, a viewing terrace 159 metres above sea level with a bunker of the Gladio network (1963–1970) at its foot. The last few kilometres take in the Costa dei Barbari, cliffs dropping sheer into the water, before the final plunge down to the Bora Village at PortoPiccolo.

Technical sequence

PortoPiccolo roads, stairs and S.P. 3 → CAI 001 / Sentiero Rilke → CAI 001a → CAI 033 → CAI 003a → CAI 003 → Grotta Dörfler → Monte Sambuco → rejoin S1 TransKarst Ultra and S1 Bora Ultra → CAI 032 → connecting sections → short stretch of CAI 010 → Lupinc Park (non-CAI) → CAI 035 → Fornace/SP 5 connecting section → CAI 010 → CAI 001 and connecting paths → short sections of CAI 023 → PortoPiccolo

The race forks

The distances starting from PortoPiccolo split at precise points, checked against the official 2027 tracks.

S1 TransKarst Ultra / S1 Half Trail, S1 Borderless Trail and S1 Family Hike & Trail — split at the start, at around km 1.2: the S1 TransKarst Ultra climbs via the old start route, while the others head down to Sistiana Bay; the tracks come together again at around km 3.0 of the S1 Half Trail.
S1 Family Hike & Trail / S1 Half Trail — split shortly after the Mithraeum, at around km 8.05; the two tracks meet again at about km 8.66 of the S1 Family Hike & Trail, which corresponds to about km 17.22 of the S1 Half Trail.
S1 TransKarst Ultra and S1 Bora Ultra / S1 Half Trail and S1 Borderless Trail — split at Medeazza, at around km 10.4 of the S1 Half Trail and km 10.2 of the S1 Borderless Trail.
S1 Half Trail / S1 Borderless Trail — split at the Grotta del Motore, at around km 13.5 of the S1 Half Trail and km 13.3 of the S1 Borderless Trail.
S1 Borderless Trail / S1 TransKarst Ultra and S1 Bora Ultra — they merge again just after Monte Sambuco, at about km 15.9 of the S1 Borderless Trail and about km 34.8 of the S1 TransKarst Ultra.