Skipper Sam Mordey said the park was gifted to the citizens of Whanganui in 1913 by Waata Wiremu Hipango.
He's taken a group there every year in the summer programme, and also does monthly trips in summer.
The park has a wharf, which needs repair, and a shelter, toilets and barbecues.
Mordey gives commentary on the 30km trip upriver, and can also take passengers on a short bush walk at the park, where there was once a pā.
People sometimes swim from the wharf or riverbank, if conditions are right.
Otherwise, the day is self-directed for passengers.
"It's very much a time for people to just enjoy being outdoors with friends and family," Mordey said.