Pure Leisure Marketing has designed an online quiz for National Express challenging users to identify where the coach company doesn't travel to.
The 'Where don't we go?' quiz invites users to comb through clues which relate to 68 destinations that National Express and Eurolines travel to. It then asks website visitors to identify the destination not served by its routes.
Prizes on offer include a year's free coach travel for two, two 30 day passes to travel anywhere on the Eurolines network and £500 spending money.
National Express has set up pages on Twitter and Facebook where entrants can find regular clues to the quiz.
Chris Dobson, head of CRM and customer insight at National Express, said: "National Express has worked really closely with Pure to deliver a campaign that is fun, engaging and drives value to the brand.
"We hope people enjoy looking for the answers as much as we did coming up with the clues."