Dolphin injuries a "freak accident" 

Marine experts say the case of a  woman, crushed by a dolphin while out sight seeing was a freak accident.

A 27-year-old Pukekohe woman was onboard a boat with four others in Slipper Island's south bay, just off the Coromandel Peninsula, when what is thought to be a bottlenose dolphin leapt out of the water in a normal display of acrobatics.

But it crashed down onto the front of the boat sending one woman through a windscreen and crushing another. The second woman received minor injuries.

The 27-year-old suffered a cardiac arrest at the beach before being flown to Auckland Hospital. She is described as being in a serious, but stable condition.

A fully grown bottlenose dolphin can weigh up to 600 kilos.

"It's definitely not something you'd want to be hit by.  It's a very solid, heavy animal... they're just muscle and bone these animals," says DOC Marine Mammal Ranger Kirsty Russell.

She says accidents like this are almost unheard of.

"It is unusual for something like this to happen...it's not been reported before in New Zealand for a dolphin to injure a human in this way."

Russell wants people to be mindful they are invading the space of wild animals when at sea. She says they should be respected and left alone.

The dolphin returned to the water, apparently unhurt.

The injured woman's family declined to speak to media, but it is understood she loved dolphins.