Hundreds of icebergs have split off Antarctic ice shelves and are drifting toward New Zealand. This could be hazardous to ships in the south Pacific Ocean, officials said Tuesday. The closest one measuring about 30 yards tall, was 160 miles southeast of New Zealand’s Stewart Island.

Navigation warnings for the area south of the country have been issued by Maritime officials.

“It’s an alert to shipping to be aware these potential hazards are around and to be on the lookout for them,” Maritime New Zealand spokeswoman Sophie Hazelhurst said.