The San Boldo Pass (in Italian Passo San Boldo, formerly Passo Sant’Ubaldo and Umbaldopass) is a small mountain pass in the Italian Veneto region between the towns Trichiana [329 m (1,079 ft)] and Tovena in the Cison di Valmarino region [272 m (892 ft)] over a distance of 17 km (11 mi).
The pass lies at the southern edge of the Alps and connects the Val Belluna with the Val Mareno over a height of 706 m (2,316 ft). The mountain pass is called the SP 635 and only one lane is passable, the traffic is regulated by several sets of lights. There is a speed limit of 30 km/h (19 mph) and a height limit of 3.2 m (10.5 ft), after buses were repeatedly stuck in the tunnel. There are five tunnels blasted into the rock with hairpin turns or loops, and six bridges.