South Western Railway (SWR) is offering journeys to more than 100 destinations for as little as £6 each way as part of its May Rail Sale, which runs from May 8 to 18.
SWR operates daily services between Exeter, East Devon, and London Waterloo.
The discounted tickets cover travel between May 23 and 31, including the half-term period and May bank holiday.
Matthew Winnie, chief customer and commercial officer at South Western Railway, said: “Our first-ever big May Rail Sale is all about helping customers enjoy great value days out and short breaks across the SWR network during the half-term and May bank holiday period.
“Whether it’s a seaside escape, a cultural city break or a countryside adventure, there are so many fantastic destinations that can be reached easily, affordably and sustainably by rail.”
Travellers can reach Exeter for £12 each way, while London journeys are also included, with the London Eye, South Bank and The Shard all just a short walk from Waterloo station.
Other discounted destinations include Southampton, Winchester, Bournemouth, Salisbury, Weymouth, Poole, Alton, and Brockenhurst.
The offer comes as new research from SWR shows a growing preference for affordable UK holidays, with more than a third of people choosing UK breaks based on cost.
Just over a quarter said they would consider swapping one holiday abroad for multiple shorter trips within the UK.
Family-friendly activities topped the list of priorities for day trips, with 57 per cent of respondents highlighting them as most important.