Rail
Slovakia's train network connects most major cities and towns, and the journey from Bratislava to Kosice (about 5 hours) passes through some beautiful countryside. Trains are affordable and generally reliable, though not fast by Western European standards. The scenic routes through the Tatras and central Slovakia are particularly enjoyable. Check schedules at cp.sk, which covers all Slovak public transport.
Bus
Buses are often more frequent and faster than trains, especially to smaller towns and mountain areas. FlixBus handles longer intercity routes at budget prices, while local bus companies (SAD) serve regional routes. The bus from Bratislava to Kosice takes about 6.5 hours but costs as little as 10-15 EUR.
Car
A rental car is the best way to explore the mountains, castles, and smaller towns. Roads between cities are generally good, and a motorway vignette is required for highways. Rural roads can be winding but are well maintained. Parking is easy outside the cities.
City transport
Bratislava has an efficient tram, bus, and trolleybus system. A 30-minute ticket costs 0.90 EUR and a day pass about 4.50 EUR. Buy tickets at machines or via the mobile app before boarding -- riding without a valid ticket risks an on-the-spot fine. For taxis, use Bolt rather than hailing on the street to avoid overcharging.