Riding the dune, about a yard high and 10 yards long, was risky, NASA scientists said. It was chosen as an alternate route around terrain -- called the "rapid transit route" -- that has been causing holes, scratches and other damage to the rover's aluminum wheels.
NASA selected a more promising route, but it included a dune-filled area dubbed the Dingo Gap, a narrow passageway between two rocky escarpments that stood in their path.
"I'm over the moon that I'm over the dune!" the rover's Twitter account tweeted Thursday, when Curiosity made its way down after spending a few days at the top of the dune.
Rover driver Matt Heverly at NASA's Jet Propulsion Laboratory in Pasadena, Calif., also tweeted his relief.
"Seeing this picture from the bottom of the sand dune put an even bigger smile on my face today," he wrote.
Both 2004 rovers Spirit and Opportunity encountered problems crossing sand. Opportunity got temporarily stuck in a dune in 2005 and Spirit became mired in a sand trap in 2009 from which it never recovered.
Curiosity is heading west to a new frontier and a new possible scientific drill target, a spot called KMS-9, NASA said.