Cluster ballooning is when a balloonist attaches themselves to a large quantity of helium or hydrogen inflated balloons via a harness and sits in a chair. Some cluster balloonists are in it for the thrilling experience while others conduct scientific research. 


Cluster ballooning is generally done in the morning because winds tend to be calmer. It can take a crew of 15 to 20 people to inflate and seal the balloons with cable ties and tape. The balloons are then tied with twine and attached to the pilot's harness. The pilot then signals the crew to release the balloons when they are ready to take off.