Hollywood director James Cameron has returned to the surface of the Earth after descending to the bottom of the Mariana Trench – a mind-boggling 11km down.

Cameron’s Deepsea Challenger is only the second vessel to have gone that far down, with the last expedition being made in 1960. Although the expedition was a success, the vessel hit the bottom of the ocean floor and stirred up silt, clouding the French-American crew’s view.

But Cameron’s endeavour was more successful – after a two-hour descent, he spent three hours filming the ocean’s deepest depths.

The Titanic director said that going on the mission was a lifelong dream. He spent the last few years working in secret to build the seven-metre long sub. The pressure on the hull of the machine was ridiculous – 1,000 atmospheres.

Cameron intends to release a documentary, but he has also done his bit for science, collecting samples of rocks and soils, and a team of researchers are working alongside the director to identify any new species.

At a time when mankind has explored near space, built a space station in orbit and is planning a mission to Mars, not many people realise that we have probably explored more outside our atmosphere, than we have in the depths of the oceans.

Mr Cameron’s multi-million-dollar expedition, which has been financed by the filmmaker himself, Rolex and National Geographic, shows that the spirit of discovery and adventure are still alive and well.

Places like the Mariana Trench were once thought to be of little interest due to the assumption of there not being any life down there, but there has been a recent resurgence of scientific interest in the deep.

Scientists are finding life that can resist the colossal pressures, from deep-sea fish to shrimp-like scavengers called amphipods, some of which can reach 30cm long.

Scientists are also trying to understand the role that deep seas trenches play in earthquakes; trenches are formed at the boundary of two tectonic plates and some believe the push and pull taking place deep underwater could be the cause of major earthquakes.

Mr Cameron says he does not want this dive to the deep to be a one-off, and wants to use it as a platform for ocean exploration. But all this exploration will be in vain if we do not change our ways. Recent reports have predicted that the Earth’s temperature could rise by as much as three degrees Celsius. Such an increase would alter life as we know it for good. This coupled with melting glaciers could have serious repercussions on our oceans, with the main fear being the proliferation of algae, which would ‘poison’ the oceans and continue to contribute to the greenhouse effect.