Underwater cameraman Roger Munns set himself and his team an incredible challenge. In 2008, they visited Tonga to film the biggest courtship ritual of the animal kingdom, the humpback heat run, for the very first time underwater and up close.

In the first few days, Roger had intimate encounters with the whales but most of the time, he was sat on the back of the boat, waiting to find a heat run. After two unsuccessful weeks, he started to wonder whether they would ever see one.

But a few days later somebody spotted a heat run, and everything sprang into action. Roger got in position and dove down ten meters underwater on a single breath. From then on, his job was just to wait and hold his camera ready. In a moment that seemed to stretch out time, he waited, nervously, for a group of 40-ton bus-sized whales to speed past him…

And Victor Vescovo describes his adventures into the deep, diving to the deepest parts of all five oceans.

Victor's longest dive was solo to the lowest point on Earth - the Challenger Deep at the bottom of the Marianas trench in the western Pacific. On reaching the bottom, some 35,853 feet below the ocean surface, should something have gone wrong, there was no hope of rescue.

Victor describes his feelings before making this historic descent and on the way down. Touching down on the sea bed, he was astounded by the abundance of marine life. Victor describes how he hopes that the mapping, observations and sample collections he has made on his dives will advance scientific understanding of the deep oceans, and where his eternal quest to explore might take him next.

Produced by Florian Bohr and Diane Hope

Credits:

Humpback whale mother and calf sounds - Acoustic Communications CNRS team & CETAMADA

Humpback whale calf sounds - Lars Bejder (MMRP Hawaii), Peter T. Madsen (Aarhus University) & Simone Videsen (Aarhus University)