IT HAS locals worried and the authorities baffled but there is still no answer to the origin of a strange noise heard deep below the icy waters in the Arctic.

Most commonly described as a “ping”, although sometimes as a “hum” or a “beep”, the mysterious sound appears to be coming from the sea floor in the narrow Fury and Hecla Strait in Canada’s remote and freezing north.

The Canadian military has scrambled aircraft to see if it can locate the origin of the noise.

It has coincided with a troubling drop in the number of migrating animals seen in the area, with some politicians concerned that whatever the noise is, it’s having a disastrous effect on wildlife.

Theories abound as to what is causing the eerie echoes with work by mining companies and military submarines, possibly foreign, floated as possible reasons.

It’s not the only perplexing sound to have been discovered emanating from the ocean depths. Scientists stumbled across another hum in the Caribbean Sea earlier this year.

Hunters in the isolated state of Nunavut were the first to hear the puzzling pulse. At 1,750,000 square kilometres, the state is larger than Western Europe but has a population of only 30,000 people, most of whom are Inuit.

The crew on a yacht passing through the strait — that divides the Canadian mainland from Baffin Island and is close to the Northwest Passage shipping route — said the sound was so loud it could be heard through the hull of a boat.

Paul Quassa, an MP in the Nunavut Parliament said the mystery sound had coincided with an alarming lack of animals in the region.

Usually, the Fury and Hecla Strait is teeming with marine life due to it being a polynya — an open sea channel in an area otherwise packed with ice.

“That’s one of the major hunting areas in the summer and winter because it’s a polynya,” said Mr Quassa.

“And this time around, this summer, there were hardly any. And this became a suspicious thing,” he told Canadian broadcaster CBC.

Another local politician, George Qualat, told CBC the strait was a migratory route for whales and seals.

“There would be so many in that particular area. This summer there was none.”

The broadcaster said it was unable to speak to anyone who had first-hand experience of the noise.

Some suspect a local mining company is behind the pings. In the past, sonar surveys have been conducted at nearby outlets but the Baffinland Mining Company has insisted nothing of the kind is taking place and there is no equipment in the area.

The finger has also been pointed at Greenpeace, with the suggestion they have put sonars in the seabed to scare away marine life and prevent them from being hunted. But the environmental group has also denied the claims.

Neither has there been any permits issued for construction, blasting or hydrography in the strait.

So suspicion has turned to the military, either domestic or foreign.

The Fury and Hecla Strait is close to Hall Beach, a military base jointly operated by Canada and the US which tracks incoming missiles across the Arctic.

Russia is also known to be testing the permeability of borders regular sending aircraft and ships close to the frontiers of NATO nations.

In 2014, a submarine was detected in Swedish waters close to the capital of Stockholm.

Suspicion immediately fell on Moscow with emergency transmissions from the vessel reported on a channel frequently used by Russia.

Both Russia and Canada have submitted claims to large chunks of the Arctic previously not owned by any country — including the North Pole.

Meanwhile, a shrinking of the ice pack around the Arctic has opened up waterways and possible maritime shortcuts close to Canadian territory that simply didn’t exist previously.

Earlier this year, the Chinese Government published a shipping guidebook to navigating the Northwest Passage which could open up a new route from the Asian nation to North America.

“There will be ships with Chinese flags sailing through this route in the future,” Liu Pengfei, a spokesman for China’s Maritime Safety Administration said in April.

The Canadian air force was so concerned it sent a military aircraft to the strait to investigate what it calls “acoustic anomalies”.

But it has been unable to solve the riddle and while it says it’s unlikely a submarine has been causing the perplexing ping, it also hasn’t ruled it out.

“The (aircraft) crew did not detect any surface or sub-surface contacts,” the Canadian Armed forces told the BBC.

“The only thing the crew did observe were two pods of whales and six walruses in the area of interest.”

Another odd undersea audible oddity was solved earlier this year in the Caribbean Sea. Researchers from the UK’s Liverpool University visited the area to study the dynamics of the sea.

But when they arrived they picked up a trace of something else, a low pulsing humming noise that while undetectable to the human ear could be picked up in space.

The phenomenon, almost like a deep heartbeat, has now been dubbed the Rossby Whistle and is a side effect of the already known Rossby Wave.

“You have a current that flows east to west through the Caribbean Sea,” Chris Hughes of Liverpool University told Gizmodo in June.

“It’s very narrow and quite strong. Just like a narrow jet of air, it becomes unstable and creates eddies.”

When waves of a certain size hit the western edge of the Caribbean basin they resonate and certain frequencies can create a sound described as an A-flat tone that’s around 30 octaves below the bottom of a piano.

But while the mystery of the Caribbean underwater hum has been solved, the cause of the Canadian ping from the bottom of the sea continues to baffle scientists.

Last week, Canada’s defence ministry said they were stumped. “The cause of the pings remains mired in mystery”.

benedict.brook@news.com.au