They were meant to arrive at the French alpine resort of La Plagne for a skiing holiday.
Instead, they ended up hundreds of kilometres away, close to France's border with Spain.
The aspiring skiers eventually arrived in the Alps a day later - and were greeted with plates of Spanish food.
"There are three entries for La Plagne in France, and I selected the wrong one," the driver told Studio Brussel radio station. Studio Brussel is the youth channel of the Flemish public service broadcaster VRT, that organised the trip.
Rather than head to the Alps, the bus driver drove from Leuven, in central Belgium, to the village of La Plagne, in the south-west of France.
The smaller, snow-free, La Plagne is near Spain, some 600km (400 miles) south-west of the ski resort.
One passenger, Sven Ceuppens, posted on Twitter: "We saw the Mediterranean and Carcassonne. #bus #lost #thirsty."
Mr Ceuppens told the BBC: "We had a hard time convincing the driver he was going to Spain and had a few laughs.
"It was a sleeper bus, so when I woke up at first light, all I saw were vineyards. Nice, but very uncommon if you want to ski.
"Immediately we knew something was wrong, but it took a map of France to convince the driver to distrust the GPS."
The bus driver turned back at Toulouse, and the group reached the correct La Plagne 24 hours late.
Organisers from Studio Brussel greeted them with plates of Spanish tapas.
Many of the tourists told Belgian television they had enjoyed the unexpected diversion.
A group of Belgian tourists were sent on a detour of close to 1,200km (800 miles) after a GPS navigation error by their bus driver.