City of Derry Airport (LDY) has flights to London Heathrow, Stansted, and Edinburgh. Belfast International (BFS) and Belfast City (BHD) are both about 90 minutes by road, with regular bus services, and give access to a wider range of routes.
Translink bus services connect Derry to Belfast (the Goldline Express takes about 90 minutes), to Dublin (about 3.5 hours), and to surrounding towns including Omagh and Letterkenny. There is no direct rail link to Belfast from the west bank — the railway station is on the east bank (Waterside), with services to Belfast via Coleraine (about 2.5 hours).