New Zealand's Doubtful Sound is one of the most beautiful places on Earth, with a magnificent landscape of lofty lakes and plunging fjords.

But it's also extremely remote and inaccessible. This is not only one of the wettest places on the planet, with 200 inches of rainfall a year, it's also surrounded by steep mountains riddled with unstable rock along five fault lines.

In 1964 more than a thousand men confronted seemingly insurmountable odds and undertook New Zealand's biggest ever construction project - to build a hydroelectric power plant under the mountains on the shores of Lake Manapouri. But soon after it was opened, it was discovered the station wasn't generating enough power; instead of 700 megawatts it could only produce 580 megawatts.

Almost thirty years later, a solution was found -- a team of brave men would again attempt to overcome the challenges posed by the remoteness of the area, the hard rock, the endless rain and the five fault lines to build another tunnel parallel to the existing one, 70 metres to the south.

'Manapouri - The Toughest Tunnel' is a compelling story of determined people battling against nature at its most unforgiving as they face the most challenging construction project ever to be undertaken in this rugged and isolated landscape.

Approx 50 minutes

All Regions - Regular 4:3 - Dolby Digital 2.0 Stereo - Colour - PAL