Five people were injured, one seriously, when their boat ran aground in Nelson today.

The boat hit a submerged object, possibly a gravel bank, while entering Port Motueka about 3.25pm, Nelson Bays Senior Sergeant Grant Andrews said.

The 44-year-old skipper from Riwaka, 5km north-west of Motueka, was flown to Nelson Hospital with a head injury and cuts to one leg.

His injuries were serious but not life threatening.

The four passengers, a woman and three children, were brought ashore by locals and the Harbour Master and treated for minor cuts and bruises.

Mr Andrews said the boat would be recovered tonight.