Fuel has been seen leaking from a boat that partially sunk while taking part in a Hawke's Bay fishing competition near the Port of Napier breakwater on Friday.
Booms were out on Saturday morning to absorb any potential diesel spill.
Four people were rescued from the 10.5 metre long recreational boat while taking part in the MegaFish event, after their boat hit a submerged log.
No one was injured, but the boat was carrying 500 litres of diesel at the time of the collision.
The vessel was towed to port and was being lifted out by a 100 tonne crane, before being taken to a nearby sailing club at the owner's expense.
One of the event's co-orgnisers Beck Christie said remnant debris from Cyclone Gabrielle had rarely been an issue over summer and this was the first incident they have had with debris since the competition began three days ago.
"People have been fishing in the bay, all over summer, and it hasn't been an issue," Christie said.
"It's just one of those fluke things, it was a submerged log under the water, it wasn't floating so it would have been pretty hard to see.
"It was just an accident, which is unfortunate."
Christie said the affected family was part of the local fishing club and was being well-supported.
"Everyone's doing fine, the club came together really well and we worked with Coastguard New Zealand on that incident," she said.
Meanwhile Maritime New Zealand issued a call to boaties to think about what can go wrong, and to check the conditions before heading out on the water for Waitangi weekend.
Recreational craft advisor Matt Wood said there had been too many safety incidents this summer, resulting in injuries, near-misses and damage.
Wood said people had fallen overboard, crashed on jetskis, and had near-misses between powered and un-powered vessels.
He said it could be a busy long weekend ahead, with the weather forecast for most of the country "quite good".
Wearing a lifejacket that fits, carrying two different types of communication devices and understanding the conditions were vital to water safety.
"However, of the incidents we have been informed of this summer, we have seen trends around not having the correct safety equipment, not following the rules and failing to understand the risks on the water," Wood said.
Record number of marlin caught in competition
A record number of marlin were caught and weighed during the MegaFish competition this year, Christie said
More than 600 anglers competed, with the biggest fish worth a $20,000 prize.
Christie said more marlin had been caught, weighed and released in one day of the competition than in a regular three-month period.
"Everyone's on a high and buzzing that there have been that amount of tagged and released marlin.
"Especially so close to the cape - normally the boats have to travel up by Māhia and Gisborne to catch those sort of fish. Really exciting for the anglers that they just have to travel half an hour to get the fish that they have been dreaming to catch."
By Saturday morning, a strong contender for the biggest fish was a marlin weighing 156kg.