Bomb dive from top of Hikitia floating crane on Wellington's waterfront

A death-defying "bomb" from Wellington's floating crane could have ended with serious injury or worse, police say.

The video of an unidentified person, who had evidently climbed the historic crane rigging before leaping into the water below, was posted on Facebook on Monday.

However, it seems the video may have been shot over two years ago.

The historic floating crane, Hikitia, was owned by the Maritime Heritage Trust of Wellington.

Trustee Malcolm McGregor said, judging by the crane's position and paint job, it appeared to have been shot before May 2013.

If someone tried the same stunt now they would slam into the steel deck below.

When the jump was made, the crane was at a height of 36 metres.

"You wouldn't know if you would survive or not from the height."

By Tuesday morning almost 80,000 people had watched it.

It was posted by Facebook group "Perth nz bombing".

Inspector Dave Rose said if the person – thought to be male – was identified, police would probably talk to him and warn him he was likely trespassing and was certainly placing himself in danger.

"All he has to do is fall climbing up or hit the boat coming down."

He estimated the jump would have been from a height of 30 to 40 metres.

"What probably seemed like a fun thing to do is probably fraught with danger."

If the jumper had hurt himself "or worse" the emergency service response would have been "substantial", Rose said.

Among the hundreds of comments on Facebook, one person described the jumper as an "idiot" but others applauded his bravery.

"Aw hek that cud have gone seriously wrong ," Facebook user "Shinade MsBlaze" wrote.

Others said it was a sub-standard "bomb" – jumping in the water with the aim of creating a large splash.

The 49m-long crane, Hikitia, first arrived in Wellington on December 21, 1926 after a delivery voyage of 82 days from Scotland.