Rescuers rushing to find the missing Titan watercraft and the five people on board are pinning their hopes on the technology they have deployed to locate and then extract the submersible from the depths of the sea.
US, Canadian and French rescue teams are already scouring the ocean and British teams have also offered help.
Here is some of the gear and equipment, some at the cutting edge and others dating back to World War II, being used in a nerve-jangling race against time.
The French-built Victor 6000 is a deepwater ROV that can sink to just under 20,000 feet.
Designed for scientific research, the submersible could dislodge the Titan if it has become stuck in the wreck of the Titanic which its passengers were travelling to observe.
The ROV could also tie a line to the stranded craft so that it can be lifted to the surface by another vessel.
Victor 6000, which has been in service since 1999, is connected to its mother ship by an electromechanical cable which is 26,250ft-long.
Canadian P-3 aircraft are active in the rescue mission and have already detected underwater noises in the search area using sonobuoys dropped into the ocean, which led to rescue operations being refocused.
The P-3 submarine hunter is described by Lockheed Martin, its manufacturer, as “the ultimate maritime patrol aircraft” .
It was used in the Cuban Missile Crisis, Hurricane Katrina and the BP Horizon oil rig disaster in the US.
The Canadian CP-140 Aurora is based on the Lockheed P-3 Orion, a four-engine aircraft developed in the 1960s with a distinctive tail stinger or “MAD” boom, which is used for magnetic anomaly detection of submarines.
The newer plane was introduced in 1980 and normally has a crew of between 12 to 15.
It has four turboprop engines and four propellers and can travel at up to 730 kilometres per hour.
The US Navy replaced its Lockheed P-3 Orion with this new maritime patrol aircraft from Boeing in 2004.
Designed for anti-submarine warfare and reconnaissance, the 129ft-long P-8 can travel at up to 564mph and carries a crew of two to seven people.
C-130 Hercules aircraft, used normally for troop transport and dating back to 1954, are also trying to detect the submarine from the air.
The far more modern P-8 can also deploy and monitor sonobuoys.
The search aircraft dropped sonobuoys into the ocean waves, 80 years after they were first used in World War II to detect Nazi submarines.
The buoys are now used in search and rescue operations to find missing planes, vessels or submarines and were how the underwater banging noises were first heard.
They are equipped with sonar, a surface float and a radio transmitter for communications with the plane. The sonar emits “pings”, which are meant to echo back off an underwater object.
The object’s location can then be worked out by the echo and is transmitted back to the surface buoy and then the aeroplane.
A 2900kg remotely operated vehicle or ROV, CURV-21 can plunge to depths of 20,000ft.
Designed to carry out deep-water salvage operations it can travel at a speed of up to 2.5 knots.
The 7ft high and 5ft wide ROV comes equipped with colour television cameras and a high-resolution black and white digital still camera.
It has sonar for target location and pinger detection. It can also be fitted with customised tool packages including salvage equipment.
The ROV will be operated from Deep Energy, a 636ft pipelayer vessel.
Two heavy-duty Hyundai winches with “6000 kg line pull” written on the side were seen arriving at St John’s airport in Newfoundland. Both winches would need to be used in tandem in order to lift the weight of the Titans.
One of three vessels, which arrived on Wednesday morning to join the search effort, has “side-scanning sonar capabilities”.
The John Cabot has a system used for “detecting and imaging objects on the seafloor”.
The National Oceanic and Atmospheric Administration said side scan sonar had multiple physical sensors called a transducer array.
“As the ship moves along its path, the transducer array sends out signals on both of its sides, sweeping the seafloor like the fan-shaped beam of a flashlight,” it said.
“Side scans search at constant speeds and in straight lines, allowing the ship to map the ocean bottom as it travels.”
Side scan sonar cannot measure depth so it is often used in combination with other tools to map the ocean floor.
The John Cabot arrived to join the search with the Skandi Vinland and Atlantic Merlin.
This seven-foot-long submersible was among vital rescue equipment flown to Canada by US air force planes to aid the rescue.
The ROV was sent by Pelagic Research Services, a Massachusetts-based company that specialises in deep-sea rescue equipment.
The company said it had been contacted to provide “critical support” to the rescue effort.
Odysseus 6K can dive to a depth of 19,000 feet and weighs less than 1720kg. It is used to install and maintain ocean observation systems, search and recovery and work tasks for industry and exploration.
It is described as a highly portable piece of equipment that can integrate easily with ship systems and is light enough to work from a broad range of boats.
It is controlled remotely from a 20-foot container that has the latest video and data-handling equipment. This control room can be fitted on the deck or interior of a ship.
The Atalante is a French ship, which was diverted from a mission to head to the search area at Emmanuel Macron’s request.
The research vessel is equipped with the Victor 6000 exploration robot and is expected to arrive on Wednesday evening after a request from American authorities.
A team from Ifremer, the French maritime research institute, will join the Atalante to operate the robot from the ship, which the submersible is connected to by a cable.
Ifremer has worked on previous Titanic dives. The Atalante was built in 1990 and hosts up to 30 technicians and scientists. It is about 277ft long and has an average operating speed of 10 knots.