Finding Shackleton's ship in Antarctica is a deeper challenge than the Franklin discovery

The Endurance22 expedition has arrived in Antarctica's Weddell Sea to search for Ernest Shackleton's ship, Endurance,the crew's Twitter feed says.

The ship was carrying Shackleton on his questto make an overland crossing of Antarctica, but was trapped in ice and sunk in 1915.The crew's fight to survive is one of the great adventure stories of its age.

The modern adventure is also significant.The challenges in finding the ship are formidable, as it's believed to be resting beneath ice in water 3,000 metres deep. The only way to reach such depths is with underwater robots.

This search is quite different from the still recent polar expedition at the top of the world by Parks Canada and the Canadian Coast Guard to find the wrecks of HMS Erebus and HMS Terror that departed England in 1845 under the direction of Sir John Franklin to search for the Northwest Passage. The ships and crew were lost.

However, the Franklin explorers were seen by Inuit on King William Island in the Canadian Arctic, and it was thanks to local Inuit knowledge that Erebus was found in 2014 sitting upright in relatively shallow water, and remarkably well preserved. In fact, the ship can be seen in summer when the ice is gone by simply looking down from the surface of the water, which has made it much easier for divers to explore.Terror was found two years later.

Modern explorers in the Antarctic may have a slightly easier time finding the location of Shackleton's ship Endurance, bit will have more difficultygetting to it. Shackleton'sexpedition carried a photographer who recorded the destruction and sinking of the vessel, while the captain used his navigational instruments to determine the precise latitude and longitude of the location of the wreck. And unlike Franklin's men, the Endurance's crew survived to tell the tale. Their remarkable story of survival, endurance and seamanship, ending in their rescue in 1916, has been often told in the century since.

Today, the remains of the ship are under the floating ice of the Weddell Sea. The expedition members, aboard the South African polar research vessel S.A. Agulhas II, will attempt to navigate through the ice as close as possible to the wreck site. They'll then deploy robotic submarines to search for wreckage.The autonomous underwater vehicles (AUVs) they'll be using are remarkable devices that can act like sniffer dogs, heading out on their own equipped with sonar and cameras to search the sea floor.

If wreckage is found, the team says it will be documented in high-resolution detail so 3D models can be constructed, and no artifacts will be removed.

It is doubtful Endurance will be as intact as the Franklin ships because photographs from the time show how badly the crushing forces of the Antarctic ice damaged it before sinking.

This isn't the first try for this team. In an expedition blog, Mansun Bound, director of exploration on the mission, wrote that he is hoping there will not be a repeat of his last trip on the same ship in 2019, when one of their AUVs failed to return, ending the search.

These historic voyages of exploration to literally both ends of the Earth are a testament to the courage and resilience of men who braved harsh conditions to map the frozen poles of our planet. It is hard to imagine how difficult these journeys were, especially now that cruise ships take tourists to these areas in luxurious comfort.