The international team worked on leadership and group skills while working as part of a typical multicultural team as found on the International Space Station, a release from the Paris headquarters of the ESA said.
There are similarities between caving and working in space, course designer Loredana Bessone said.
"The 'cavenauts' have to adapt to a completely new environment," she said. "Working and living underground is both physically and mentally demanding."
The course was a chance to practice space protocols, Bessone said.
"Cavewalking is similar to a spacewalk," she said. "You have to pay continuous attention to the correct use of tools and safety protocols, to the progression path and to obstacles, which correspond to No Touch Zones and Keep Out Zones on the Space Station."
Participants in the six-day cave expedition included astronauts from the United States, Japan, Canada, Russia and Denmark.