Bad behaviour by jetski riders has brought an official warning that the machines must be operated responsibly - and not by unsupervised young people.
Northland deputy harbourmaster Chidambaram Surendran said yesterday a number of fairly serious incidents involving jetskis had been reported around the region this summer, including one young man who allegedly drove into the Marsden Cove marina at speed and another where a jetski sped past boats moored at Tutukaka.
Other incidents had included children being towed behind jetskis on a biscuit without a proper lookout and others travelling at speed close to rocks or riverbanks in narrow coastal areas.
The Marsden Cove incident involved a jetski carrying two people zooming into the marina at the weekend. The machine had pulled up at a pontoon and the young man at the controls was reported to have gone ashore before he and his passenger drove away.
Mr Surendran said marina staff and police were looking for the jetski. The same rider was suspected to have been involved in a jetski incident at Waipu Beach late last year.
At Tutukaka, an Auckland man with a young passenger had been reported driving a jetski at more than 20 knots past moored boats in the harbour on January 4.
The rider had been issued with a written warning that jetskis have a 5-knot speed limit within 200m of the shore or 50m of another vessel, craft or person.
Mr Surendran said jetski registration was compulsory under the Northland Regional Council's navigation safety bylaw. People flouting the bylaw risked an instant fine of $200.
"As well as helping locate anyone seen breaking our safety bylaws, registration is also a useful way of identifying jetskis if they're stolen."
By mutual agreement over the past few years, the Auckland Council maintains a single register of jetskis used in the Auckland, Northland and Waikato regions.
Registration costs $35 and involves completing a form available from regional councils or their websites.
Registration with the Auckland Council is valid in all three regions for the life of the jetski. The registration number needs to be displayed on each side of a jetski. Stickers can be supplied for $12.50 or the number can be signwritten on the jetski by the owner so long as each digit is at least 90mm high and 80mm wide and clearly visible.