InterRail (www.interrail.eu) offers unlimited first- or second-class travel in up to 30 European countries for European residents of over six months. The Global Pass allows travel across all 30 countries, for 15 days, 22 days, one month, five days in 10 days or 10 days in 22 days. However, there is no One Country Pass available for Montenegro, and on this pass, travel is not allowed within the passenger's country of residence. Travellers under 26 years receive a reduction, and children's tickets are also discounted about 50%. Supplements are required for some high-speed services, seat reservations and couchettes. Discounts are offered on Eurostar and some ferry routes. Available from Rail Europe (www.raileurope.co.uk).