A Dutch-registered coach overturned on the M3 in Hampshire after the driver lost consciousness at the wheel.
Eight people were being treated in hospital following the crash, which happened on the southbound carriageway a mile from Fleet services at about 6pm on Sunday.
The vehicle was filled with 26 cruise passengers on their way to set sail from Southampton, Hampshire Police said.
One person suffered a fracture, while seven others received minor injuries, a force spokeswoman said.
All the passengers were Dutch nationals, she added.
Sgt Lyndon Barrett said: "It appears that the driver became unwell at the wheel and lost consciousness and lost control of the vehicle.
"Miraculously, only eight people were hurt; five have been taken to hospital as a precaution, but nobody seriously hurt this time."
He added: "Passengers have been conveyed to hotels in Southampton where they will meet a cruise ship (on Monday)."
The coach was left lying on its side in bracken after veering off the carriageway.
The motorway was closed to allow the injured to be taken to hospital and to enable police to recover the overturned vehicle.
One southbound lane has since reopened but drivers are being advised to avoid the area because of long tailbacks.