"He is still quite traumatised and confused by the whole experience and very fearful," the detective said. "We will be speaking to him again [today] to get a more accurate picture of what happened."
Police inquiries are continuing and officers will also be looking through CCTV footage from the area to see if the attacker can be spotted.
The detective said anybody who may have seen the man walking on Riverside Drive before the attack, or who may have seen anybody acting suspiciously in the area around that time, to get in touch. Also, if anybody found a knife in or around the Town Basin and Riverside Drive area, they are to contact police immediately.
The stabbing was the third major crime to involve a knife in Whangarei in just over three days, but there is no evidence the three incidents are linked.
A Whangarei pizza-delivery man is too terrified to go to work after he was robbed at knifepoint on Wednesday. The aggravated robbery was one of two in Whangarei within hours of each other in which victims were held up at knifepoint. The robber was described as a male Maori, of slim build and about 1.7m tall.
He was wearing a cap, a black bandanna, a blue tracksuit top and white-soled sport shoes.
Earlier in the day, police were called to an aggravated robbery in which a 23-year-old woman walking through Tawera Park near the skate bowl, about 4.30pm, was confronted by a man with a knife. He took her cellphone and credit cards.
The robber then ran through the park towards Maunu Rd and was last seen near the hospital. The man was described as dark-skinned, of medium build, and about 1.65m tall, wearing a blue hoodie, with the hood up, and black sunglasses.
Information on Saturday's stabbing, or any of the other knife crimes can be passed on to Whangarei police on 4304500, or anonymously through Crimestoppers on 0800 555 111.