Diary: New Guinea's secret species

The team is filming in the little-explored forests of New Guinea

An international team of explorers and scientists is on an expedition to the forbidding jungles of New Guinea.

They plan to survey a lost world of volcanoes, caves, mountains and rivers in search of the strangest animals on the planet.

They will have to endure one of the toughest jungles on Earth to step where no scientist has set foot before.

A successful expedition could result in this unique forest being safeguarded forever.

In this weekly diary, the BBC Natural History Unit crew accompanying the researchers will share their adventures.

MONDAY 23 FEBRUARY - LOST WORLD

Twelve months of planning came to a head this week as we finally ventured into the heart of Mount Bosavi.

Helicopter flies the explorers into the centre of the volcano

An extinct volcano blanketed by thick jungle, Bosavi has steep fortress like cliffs protecting a four-kilometre wide crater at it's centre.

We managed to find a weather window and land a helicopter inside.

No outsiders have spent time in this lost world, no scientists have ever been here, and even the scattered local population rarely enter the crater. We all felt this was a truly original exploration.

The crater is paradise found. We are camped next to a crystal clear, fast flowing river, whose water we bathe in, swim in and drink - all at the same time.

Surrounded by pristine rainforests, there are no signs of human life apart from our own and every rock is draped with green moss.

Up close and personal with a tree kangaroo

In this Eden animals are completely na