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Undersea mining was the stuff of fantasy in the 1800s when Jules Verne wrote the classic novel 20,000 Leagues Under the Sea.
But it is not such a strange concept for Perth-based company Bonaparte Diamond Mines, who is one of several companies dredging for diamonds off the African coast.
Bonaparte is Australia's only marine diamond miner, and one of only a hand full of similar operators in the world.
However, it is not only diamonds that Bonaparte's executives are excited about.
As part of digging for diamonds Bonaparte have discovered something else of value in the process.
Bonaparte's chief executive Mike Woodborne says the southern African nation of Namibia, on the Atlantic coast is well known for its unique deposits of gems.
"Off the coast in Namibia it's renowned as a world unique deposit of gem quality diamonds," he told AM.
"The diamonds have travelled 1,000 kilometres from the hinterland of Africa down mighty rivers like the Orange, where they've been tumbled through quite strenuous environments, only the best-quality survive.
"So off the coast of Namibia you'll find 95 per cent gem quality diamonds strewn on the beaches above and below the present sea level."
Bonaparte has also discovered the seabed off Namibia is rich in marine phosphates which can be used to make fertiliser.
"We've known about our potential for marine phosphates off the coast of Namibia for a while," Mr Woodborne said.
"Developing these comes as a natural extension of our marine investigations into exploration and mining of diamonds and it's been a great development that the price has changed, making the commodity now a viable consideration for the company."
While undersea mining may sound like Jules Verne stuff, many people would be surprised to know it is an exercise that has been going on for some time.
Mr Woodborne says the dredging techniques used in mining undersea phosphates and diamonds are becoming standard practices.
"Certainly in the diamond sector that's been happening since the early 1960s," he said.
"But more so in the case of our marine phosphate projects, what we're dealing with is the standard of marine dredging which is happening around the world in many places, in Hong Kong and Singapore, Dubai.
"Where we're dealing with a movement of material off the seabed as a standard dredging process which the Dutch and the Belgians have been masters of for many, many years now."
Mr Woodborne says despite the operations taking place out to sea, the work is now well understood.
"These particular project areas are going to be approximately 40 kilometres off the coast in an environment which operations have been ongoing in the marine diamond industry for many years now," he said.
"So the operational environments are pretty well understood."
Environmental impact
As has been seen recently in Australia with the Port Philip Bay project, dredging can be a controversial practice because of its potential impact on the environment.
However, Mr Woodborne says that because diamond mining and dredging is such an established practice in Namibia, there is legislation in place to effectively manage the industry.
"Namibia must be one of the few countries in the world that has established a marine diamond mining industry, or offshore diamond mining industry," he said.
"They've got well placed legislation, management programs et cetera to establish baselines, so certainly there will be minor impacts.
"It all comes down to what percentage of that environment that we are going to be influencing and in those vast areas of the coast we are likely to be only influencing a very small percentage of the ground.
"We'll do so in terms of established mining practices with the Namibian Government."
Measures are also taken to rehabilitate the areas once dredgers have gone through and scraped the undersea surface.
Mr Woodborne says practices applied in the diamond mining industry aim to replace a large proportion of the material that is not needed in the final product.
"It's a case of putting the tailings directly over the ground that's been mined so it's almost an immediate replacement of a large portion of the material," he said.
"After that it's allowing the ocean to do its normal work of regenerating itself and re-establishing itself."