Bovec and Piran are 108 miles (174 km) apart, making this incredibly scenic trip from the alps to the seaside very doable in one trip. With that being said, the fastest and most convenient way is by car—private transfer or rental—at just about 2.5 hours. As a bonus, this route takes you right through Slovenia’s western wine region.
The other option is to travel by regional bus, but this will require a lengthy journey (over 7 hours) due to limited timetables, plus connections in the capital city, Ljubljana.
By Private Transfer or Rental Car
Duration: 2.5 hours
The most convenient and fastest option is by car. Private transfers are available in Bovec, but keep in mind that rental cars are not. So although it may be more convenient to have your own vehicle, you’ll need to obtain it prior to arriving in Bovec. Rental cars are available in many other towns and cities in Slovenia.
The driving route itself is simple and scenic. After leaving Bovec, you’ll drive through the beautiful Soča River Valley via Route 102/203. Once you reach Tolmin, you’ll head south through Slovenia’s western wine country via Route 103 and the H4 expressway.
Eventually, you'll connect to the A1 highway which takes you to the coast. Piran is just off Route 111, but keep in mind that Piran’s old town is almost car-free. There is plenty of paid parking near the old town for this reason, including two lots near the port and three up on the hill by the old walls.
If staying in Piran, many accommodations offer shuttles to the parking areas, or you can utilize the town's own public transportation. It's best to have a little cash on you for parking and bus fees.
Some great options for a lunch break along the way include Kobarid and the cultural heritage village of Šmartno. If you’re interested in visiting a winery, there are plenty along the H4 expressway between Nova Gorica and Razdrto, or in the Goriška Brda region west of Route 103. Additionally, some of Slovenia’s famous caves, including Postojna Cave, are just a short detour (15 minutes) from Razdrto.
Duration: 7+ hours
A slower and less convenient option is to take the regional bus. The only way to accomplish this route in a day requires a transfer: four hours from Bovec to Ljubljana, and then 3 hours from Ljubljana to Piran. And with limited timetables, you’d have to catch the 7:30 am bus from Bovec and wait for 3.5 hours before the last bus leaves Ljubljana at 3:00 pm.
Ljubljana is worth a visit in itself, so you can always use your connection time to explore the capital city, or even spend the night. If doing the latter, you can take a later bus out of Bovec and an earlier bus the next morning to Piran.