Titan, previously named Cyclops 2, was a submersible created and operated by the American underwater tourism company OceanGate. It was the first privately owned submersible with a claimed maximum depth of 4 kilometers (13,000 ft; 2.5 mi), and the first completed crewed submersible with a hull constructed of titanium and carbon fiber composite materials.
After testing with dives to its maximum intended depth in 2018 and 2019, the original composite hull of Titan developed fatigue damage and was replaced by 2021. In that year, OceanGate began transporting paying customers to the wreck of the Titanic, completing several dives to the wreck site in 2021 and 2022. During the submersible's first 2023 expedition, which took place in June, all five occupants were killed when the vessel imploded. OceanGate lost contact with Titan on 18 June and contacted authorities later that day after the submersible did not return on schedule. A massive international search and rescue operation ensued and ended on 22 June, when debris from Titan was discovered about 500 metres (550 yd; 1,600 ft) from the bow of the Titanic. The incident became widely discussed on social media as the story developed, and inspired grimly humorous Internet memes that ridiculed the submersible's deficient construction, OceanGate's perceived poor safety record, and the individuals who died. The memes were criticized as insensitive, with American TV presenter David Pogue deeming them "inappropriate and a little bit sick".
Industry experts, friends of OceanGate CEO Stockton Rush, and OceanGate employees had stated concerns about the safety of the vessel. The subsequent investigation by the U.S. Coast Guard highlighted serious safety concerns, criticizing OceanGate's operational practices and identifying a "toxic workplace culture" in which safety warnings were suppressed. The report concluded that Rush "exhibited negligence that contributed to the deaths" and created a false impression of the submersible's safety.
Since the discovery of the Titanic wreckage in 1985, limited tours of the wreck have been conducted, including the (Finnish-made) Russian Mir-class submersibles in the 1990s, which captured the footage for the opening scenes of the eponymous 1997 film.
After carrying tourists to the wreck of Andrea Doria in 2016, OceanGate CEO Stockton Rush said "there's only one wreck that everyone knows... if you ask people to name something underwater, it's going to be sharks, whales, Titanic." OceanGate's Titan was used for several survey expeditions of the Titanic wreckage site, starting in 2021. Rush stated that Titan could be used to explore the debris field and build a 3-D model of the wreck.
Titan was 670 by 280 by 250 centimetres (21 ft 11.8 in × 9 ft 2.2 in × 8 ft 2.4 in) and weighed 9,525 kilograms (21,000 lb) with a maximum payload of 685 kilograms (1,510 lb). It moved at up to three knots (5.6 km/h; 3.5 mph) using four electric thrusters, arrayed two horizontal and two vertical. According to OceanGate, the vessel carried sufficient oxygen to sustain a full complement of five people for 96 hours.
The entire pressure vessel for the crew used five major components: two hemispherical titanium end caps, two matching titanium interface rings, and the 142-centimetre (4 ft 8 in) internal diameter, 2.4-meter-long (94 in; 7.9 ft) carbon fiber-wound cylindrical hull. The forward hemispherical end cap could be detached from its interface ring, becoming a hatch that allowed crew members to enter the crew compartment before a mission, and exit at its conclusion. In addition to the crew compartment, Titan included a landing skid structure and an outer fiberglass composite shell covering mechanical equipment; both the skid and shell were bolted to the titanium interface rings.
OceanGate's calculations showed the cylinder that formed the center section of the crew compartment should have a wall thickness of 114 millimetres (4.5 in), which they rounded up to 127 millimetres (5.0 in); it consisted of 480 alternating layers of pre-preg unidirectional cloth, laid in the axial direction, and wet-wound filament, laid in the hoop direction. Spencer Composites completed the design and assembly of the cylinder in 2017 after curing it at 137 °C (279 °F) for 7 days.
Each titanium end cap had a wall thickness of 83 millimetres (3+1⁄4 in). One interface ring was bonded to each end of the cylindrical hull, and the end caps were bolted to the interface rings. The penetrations for external cables ran through the interface rings. The forward end cap was fitted with an experimental 380-millimetre-diameter (15 in) acrylic window, shaped as a modified conical frustum 180 millimetres (7 in) thick. According to Rush, it would protrude into the cabin by 19 millimetres (3⁄4 in) during dives. The viewport was rated only to 650 metres (2,130 ft).
Titan was equipped with a real-time acoustic monitoring system, which OceanGate claimed could detect the onset of buckling in the carbon fiber hull prior to catastrophic failure. Rush held a patent on the system. Titan was controlled with a modified game controller, similar to Cyclops 1.
Once the occupants were aboard, the hatch was closed and bolted from the outside; there was no way to open the hatch from inside the vessel. In addition, there was no on-board location system; the support ship which monitored the position of Titan relative to its target would send text messages to Titan providing distances and directions.
OceanGate began developing a composite carbon fiber and titanium-hulled submersible in collaboration with the University of Washington's Applied Physics Laboratory (APL-UW) in 2013, tentatively named Cyclops 2; the first titanium structural components were ordered in December 2016 from Titanium Fabrication Corp. (TiFab), and OceanGate signed a contract with Spencer Composites in January 2017 for the carbon-composite cylinder.
Spencer previously had built the composite pressure hull for the single-person DeepFlight Challenger for Steve Fossett to a design by Graham Hawkes. Spencer Composites was given challenging performance targets for Cyclops 2, which was meant to withstand 6,600 pounds per square inch (46 MPa; 450 atm) working service pressure with a factor of safety of 2.25× for its intended maximum depth of 4,000 metres (2.5 mi; 13,000 ft), and provided six weeks to complete the design. In March 2018, Cyclops 2 was renamed to "Titan"; and Rush described it "an amazing engineering feat" during its launch in 2018.
In an interview published in 2020 with Teledyne Marine, a subsea technology company, it was noted that many Oceangate employees were recent graduates. Rush responded that he, unlike other submarine enterprises, "wanted [his] team to be younger, be inspirational" instead of including "ex-military submariners", who he described as "a whole bunch of 50-year-old white guys".
In 2015, when Rush visited DOER Marine seeking lessons learned from "Project Deep Search", DOER's president, Liz Taylor, specifically warned him against using carbon fiber; in 2023, she recounted that carbon fiber specifically has "been shown to not be very happy when it's being immersed first of all and then being hollow on the inside or just one atmosphere on the inside and then having the tremendous pressure of the ocean trying to push in on it, it's not the right material".
The Marine Technology Society's committee on Manned Underwater Vehicles (now called Submarine Committee) drafted a private letter to Rush in March 2018, expressing concerns with the design of Titan and urging him to have the ship "classed" (certified by a ship classification society), partly because the marketing of the submersible, which stated it would meet or exceed the standards of DNV, was misleading because OceanGate had no intentions to have the vehicle tested by DNV. There were 38 people who agreed to have their signature on the letter. Although the letter was not sent, the chair of the committee, William Kohnen, said he had "a frank conversation" with Rush following which they "agreed to disagree".