Containers and debris could spill into the sea as waves up to 8m high batter the wreck of the Rena this week, authorities say.
Forecasters said a series of tropical storm systems causing flooding and slips in Fiji are set to hammer the Bay of Plenty tomorrow and Wednesday.
Weatherwatch.co.nz said the wreck of the Rena on Astrolabe Reef could be in the firing line for waves averaging four metres high.
Oceanographer Brett Beamsley said maximum individual waves could exceed seven metres high.
Gale force winds were predicted in the area, though there was still some uncertainty in weather models, he said.