A 25-year-old soldier was injured after falling 5 metres into a dry riverbed near Dannevirke.
The incident happened during a crossing of the riverbed as part of a military night training exercise about 10pm.
The soldier was carried out of the river by fellow soldiers and the Palmerston North Rescue Helicopter was called.
Paramedics on board attended to the soldier as he was flown to Palmerston North Hospital.