'I'm a little worried': Video of final White Island tour before eruption shows chilling moment guide realises something's off

A dramatic extended video of the last tour on White Island reveals a guide's concerns about the volcano just before the deadly eruption.

The eerie video, posted to YouTube by Brazilian tourist Allessandro Kauffmann, shows the final tour group being taken around the island.

But in a chilling moment during the clip, someone can be heard saying, "I'm a little bit worried why it's going green", as the camera points to green water on the ground.

The group then leave on the boat, which is when smoke can be seen pouring from the island.

Then the panic starts.

"Man, that's terrifying. You can't tell your mum this happened," one woman is heard saying. By this stage, the island is no longer visible due to the smoke.

Ten minutes after leaving the island, the tour boat turns back to help rescue people from the devastating eruption.

Kauffman told The Project on Tuesday he was one of the first to see and film the eruption.

He and his partner Aline Moura saw people lying on the rocks and noticed the surrounding water had turned white.

"Everyone was covered in [ash]... everything was grey," Allessandro said.

"Some people were very, very seriously injured."

Eight people are now confirmed dead following the eruption on Monday. 

Authorities plan to return to the island to retrieve bodies on Friday.