James Cameron gets ready to dive to the Mariana Trench

Hollywood director James Cameron may be close to making a dive to the deepest place on Earth.

In a one-man submarine, he plans to dive 11km (seven miles) down beneath the waves to the bottom of the Mariana Trench, in the western Pacific.

There has only ever been one dive there, and that was half a century ago.

The BBC's science reporter Rebecca Morelle reports from near the dive site in Guam.