Ten couples got into the Valentine's Day spirit on Friday 13 February in the World's Longest Dance Marathon competition in Pattaya, Thailand.
They are aiming to break the Guinness World Record set by a Mexican couple in 2008 of 35 hours.
The couples have to dance and move their feet continuously in three different rhythms: waltz, cha cha cha and rumba.
The organisers said it is difficult to keep moving for a long time, although each couple can have a five-minute break every hour.
"Now I'm feeling OK. The most important thing is to drink, so I take some sugar in my blood and be better now," said participant Karin Lanteri from Canada.
"I think the first three hours [are the most difficult] because you have to get the good rhythm with your partner, to be alert with the music, to feel the music, to understand the rhythm of the music," said Olivier Dufour, who also holds a Canadian passport.
The winner will take home THB200,000 (£3,984, $6,128) and a diamond ring. The competition is due to finish at the 35th hour and one second on 14 February at 10.01am.