The Titan submersible is lost on a dive to the Titanic

A deep-sea tourist submersible named Titan was lost this year during a dive to the wreck of the Titanic, imploding in the crushing pressures of the deep ocean and killing all five people aboard, in a tragedy that unfolded amid a gripping international search that captivated and then saddened the world.

The small submersible, operated by a private company offering expeditions to the famous wreck lying thousands of metres down in the North Atlantic, lost contact with its support ship during its descent, triggering an urgent search-and-rescue operation across a vast and remote stretch of ocean.

For days, the world followed the search with mounting anxiety, as vessels and aircraft from several countries scoured the area and as attention focused on the dwindling air supply aboard the craft, if those aboard were still alive. The ordeal gripped global attention.

The search ended in tragedy when debris from the submersible was discovered on the ocean floor near the Titanic wreck, indicating that the craft had suffered a catastrophic implosion, almost certainly killing those aboard instantly, likely during the descent.

The disaster raised serious questions about the safety and regulation of the nascent industry of deep-sea tourism and about the design and oversight of the submersible, which had operated outside the usual certification regimes for such craft. Experts had reportedly raised concerns about its safety.

The loss of the Titan became one of the year's most closely followed world stories, a tragedy that underscored the extreme dangers of the deep ocean, one of the least explored and most hostile environments on Earth, and prompted scrutiny of the risks of adventure tourism at the frontier of human exploration. The episode was a sombre reminder of the perils that lie in the ocean's depths, and of the fragility of human endeavour against the immense forces of nature.