Safety communications related to TSB investigation M23A0169: June 2023 implosion of the Titan submersible and loss of life

The occurrence

On June 18, 2023, the Titan submersible, owned by U.S. based company OceanGate, imploded while descending to the wreck of the Titanic with five people on board. At the time of the occurrence, the operation was supported by a Canadian cargo vessel, the Polar Prince, operated by Canadian company Horizon Maritime Services Ltd., which towed the Titan from St John’s, Newfoundland and Labrador, to dive locations, as well as providing a base for OceanGate’s operations. Horizon Maritime also provided this service to OceanGate in 2021 and 2022.

Safety communications

Canada’s approach to regulatory oversight

Under the Canada Shipping Act, 2001, Transport Canada (TC) is responsible for marine safety, security, and environmental protection in relation to Canadian vessels and foreign vessels operating in Canadian waters. Regulatory oversight from TC provides independent verification of the safe operation and regulatory compliance of these commercial vessels through inspections either for mandatory certification where required, or compliance with regulations.

How TC identifies vessels and provides oversight depends on whether a vessel is Canadian- or foreign-registered and on its size:

• Approximately 25% of the Canadian fleet,This percentage is based on information obtained from the Canadian Register of Vessels. which includes vessels of more than 15 GT or carrying more than 12 passengers, requires a certificate to operate. To receive the required certificate, vessels must successfully pass an inspection by TC marine safety and security (MSS) or a TC-authorized recognized organization. Authorized representatives (are responsible for the regulatory compliance and safe operation of their vessels. Part of the regulatory compliance is to initiate inspections.
• The remaining domestic vessels, which account for 75% of the Canadian fleet, do not require a certificate to operate. While ARs remain responsible for regulatory compliance and safe operation of their vessels, TC does not conduct mandatory inspections to verify compliance. Instead, oversight of these vessels includes “risk-based inspections”, a term that is used extensively on the TC website and in correspondence from the department. However, there is limited information to indicate what degree of risk or what vessels or operations trigger these inspections.  
• TC monitors the entry of foreign vessels sailing into Canadian waters using data from pre-arrival notification systems. It then uses data from different sources to identify which foreign vessels to inspect. Foreign vessels arriving in Canada are selected for boarding and inspection in accordance with international Port State Control (PSC) guidelines.
• Smaller foreign vessels under international tonnage thresholds (500 GT), vessels carried as cargo, and other smaller vessels are not captured by the PSC ship inspection program. TC may visit such vessels if they receive reports that raise concerns or may act based on their own observations.

The Titan entered Canada a number of times. However, it was not captured in PSC pre-arrival notification systems, due to its size and its means of arrival in Canada (by road, as cargo on another vessel, or under tow). Although TC was aware that the Titan was operating from St. John’s and that it was supported by Canadian vessels, it was unaware that the Titan was not registered with any flag state. TC discussed Horizon Maritime Services Ltd operations, primarily to determine whether the Titan was to be considered a vessel and consequently whether action from TC was required. It determined that the support vessel was Canadian and certified, and concluded that appropriate regulatory oversight was in place for the Titan and its operations. However, this was not the case; and TC’s risk-based approach to determine the level of oversight required, resulted in no action taken and no oversight of OceanGate’s operations.

This situation is not unique: approximately 75% of Canada’s commercial fleet falls under the same risk-based oversight model and is not required to have a valid safety certificate to operate. As a result, many vessels receive little, and in some cases no, oversight from TC. 

The investigation found that Canada’s approach to regulatory oversight to identify safety deficiencies resulted in increased risk to those involved in the Titan’s operations. Since 2015, the TSB has determined that a lack of regulatory oversight was a factor in several occurrences involving uncertified and unregistered fishing vesselsTSB marine transportation safety investigation reports M21A0315, M20A0160, M19A0090, and M16A0327. and uncertified tugs.TSB marine transportation safety investigation reports M21P0030, M20P0230, M17P0244, and M15P0037. 

Given that uncertified vessels, such as the Titan, are often not subject to any regulatory oversight in Canada, the Board recommends that

The Board also recommends that 

Information sharing between Transport Canada and other government departments 

Under the Canada Shipping Act, 2001, TC is responsible for marine safety, security, and environmental protection in relation to Canadian commercial vessels and foreign commercial vessels operating in Canadian waters. Inspections to Canadian vessels requiring certification and foreign vessels of 500 GT or more are scheduled according to TC and PSC guidelines, respectively. Outside of these scheduled inspections, oversight and enforcement depend on external reports to TC or its own observations. For all other vessels, vessel identification and oversight depend on risk-based inspections, on reports to TC, or on TC observations. 

The nature of marine operations requires vessels, owners and operators to interact with other government entities in addition to TC, such as the Canadian Border Services Agency (CBSA), Fisheries and Oceans Canada (DFO), provincial authorities, and port authorities. Previous TSB investigationsTSB Marine Transportation Safety Investigation Report M20A0160. have identifed a lack of information sharing between departments and this occurrence was no different. 

In the case of the Titan, OceanGate conducted dive operations to the Titanic wreck (in international waters), as well as in Canadian waters and in Canada’s exclusive economic zone (EEZ), from 2021 to 2023. A number of Canadian government departments, including DFO, interacted with OceanGate from 2019 up until the time of the occurrence.These departments were TC (Marine Policy branch), Parks Canada, DFO, MSOC, Environment and Climate Change Canada, Natural Resources Canada, CBSA, the Department of National Defence, and the Royal Canadian Mounted Police. These government departments had varying levels of knowledge of OceanGate’s operations, and some had information that might have been useful to TC in assessing risk and determining the appropriate level of oversight. For example, DFO was aware that some of the Titan’s operations were taking place in Canadian waters and its employees raised safety issues related to construction and operations internally. The CBSA had granted OceanGate permission to use its equipment, including the Titan, for scientific expeditions in Canada. However, TC was not aware that the Titan was operating in Canadian waters.

The investigation found that there is limited information-sharing between TC and other government departments, which results in TCThe Marine Policy branch of TC had interacted with OceanGate. However, the Marine Policy branch is not responsible for marine safety and security. missing opportunities to access information that could be useful in assessing risk in commercial vessel operations and determining the appropriate level of oversight.

Therefore, the Board recommends that 

Oversight of submersibles

Submersible operations may be subject to oversight either through classification by a recognized classification society or through registration with a flag state that regulates submersibles. Some countries, including The Bahamas, the Cayman Islands, and Japan, require submersibles to be classed, while others have regulatory frameworks governing their operation. In contrast, some countries, such as Canada, have limited oversight requirements. For example, Canada requires only that operators of passenger-carrying submersibles and engineering crew members hold valid certifications.

Marine regulatory regimes are generally designed for at-surface commercial vessels, particularly those subject to certification or port state control. Because submersibles are typically small vessels and are often transported as cargo, ship’s equipment, or by tow, they may fall outside many traditional regulatory frameworks.

International standards for maritime safety are established through the International Maritime Organization (IMO). The IMO has issued guidelines for the design, construction, and operation of passenger-carrying submersibles (MSC Circular 981).International Maritime Organization, MSC Circular 981 – Guidelines for the Design, Construction and Operation of Passenger Submersible Craft (29 January 2001). The guidelines for operations include recommendations about safety management systems and procedures for emergency responses. However, this guidance is not incorporated into international conventions or codes. As a result, it is only binding at the national level where member states have incorporated it into domestic regulations.  

As a result, oversight of submersible operations relies largely on individual flag state requirements, and safety depends significantly on the voluntary actions of owners and operators. This fragmented approach can increase risks to those involved in submersible operations, as well as to vessels and the marine environment. As Canada's representative at the IMO, TC is positioned to advocate for the development and adoption of stronger international safety standards for submersibles.

Therefore, the Board recommends that 

In Canada, submersibles are included in the definition of a vessel under the Canada Shipping Act, 2001 and therefore subject to the same regulatory oversight as other vessels. However, there are no comprehensive or specific regulations in Canada that govern the construction or the operation of human-occupied submersibles, although there are regulations regarding crewing.

In response to concerns raised in 2004 regarding passenger submersible operations in the Haliburton Forest and Wildlife Reserve, Haliburton, Ontario, TC created an internal policy on domestic passenger submersiblesTransport Canada, Tier 1 – Policy: Passenger Submersible Craft, 2005. with the objective of implementing the IMO’s guidelines for passenger submersibles (MSC/Circ. 981). This policy applies to all non-pleasure passenger submersibles engaged solely on domestic voyages. Although it was in effect during the Titan’s operations, it was not applied to assess them. The investigation established that various factors contributed to the policy not being applied, including TC’s limited knowledge of the operations as well as the limited awareness of this internal policy among TC officials.

In April 2026, TC released Ship Safety Bulletin (SSB) 03/2026: Requirements for passenger submersibles operating in Canadian waters. The SSB identifies an approach to TC’s oversight of submersibles, using instruments, norms, and standards that existed at the time of the Titan’s operation, and adds reporting requirements for dive operations.

The investigation identified that, in addition to the Titan, there have been other human-occupied submersibles operating within Canadian waters and the Canadian EEZ, both before and after the Titan’s implosion. In 2024, the TSB issued a marine safety information letter (MSI 01/2024), informing TC that submersibles were operating within Canada and noting that only some of these were registered in Canada or with other flag states. Given the gaps in TC oversight of submersible operations, and the risks associated with these operations, it is necessary that changes be made to enhance safety in this area.

The implementation of MSC/Circ. 981 through the TC policy on passenger submersibles and the publication of new and existing requirements in SSB 03/2026 are both steps in the right direction. However, SSBs and policies are intended to guide behaviour and are not enforceable. It is unclear if these steps will mitigate the risk associated with the operation of a vessel such as the Titan in the future. 

Without mandatory oversight of all human-occupied submersibles, the underlying risk remains. In this investigation, the Board found that both oversight that relies largely on owners and operators taking the initiative to seek it out and a lack of detailed emergency response plans to manage all possible emergency scenarios, including readily available and proven rescue resources, increase the risk to all those involved in the submersible’s operations. 

Therefore, the Board recommends that.

Safety management system practices for one or more groups working on a vessel 

The Polar Prince was regularly chartered to various groups for different purposes, including educational voyages, documentary filmmaking, and support for expeditions, such as the one being conducted by OceanGate. When chartered to OceanGate, the Polar Prince carried OceanGate passengers and equipment and towed the Titan and its launch and recovery system.

For operations involving multiple groups, there are often interactions between a vessel’s safety management system (SMS) and the safety management processes used by other parties. To ensure that responsibilities are clearly defined and that safety and emergency response activities are coordinated, organizations commonly develop bridging documents.

A bridging document is intended to 

• define the roles and responsibilities of all persons involved,
• ensure that appropriate procedures are in place for all operations,
• clarify whose procedures take precedence when procedures overlap,
• ensure that all operations are assessed for risk as effectively as possible, and
• ensure that effective emergency response arrangements are in place.

The Polar Price operated under an SMS that complied with the ISM Code; and Horizon Maritime Services Ltd, the company operating the Polar Price, also had an emergency response plan that specified that customer-specific emergency response requirements should be addressed through a bridging document and a joint emergency response plan. However, for operations such as those conducted by the Polar Prince and OceanGate, there is no external requirement to develop a bridging document.

A bridging document is also essential for clarifying the master’s authority when it comes to the safety of the vessel and those on board. When one or more groups are working on board a vessel for specialized operations, as in the case of Horizon Maritime Services Ltd. and OceanGate, the master may have to interact with differing and ambiguous instructions from the different groups. For this reason, the master’s authority needs to be clearly defined in the SMS and supported by management, especially in the context of decisions relating to vessel operations and charter considerations. 

When the Polar Prince was chartered to OceanGate, there was an understanding among both the Polar Prince crew and OceanGate personnel that OceanGate’s operations would be treated separately from the Polar Prince’s operations and would not be covered by the Polar Prince’s SMS. The rationale was that the submersible operations were outside the realm of expertise of the Polar Prince crew. Consequently, neither group reviewed the other group’s procedures, and no bridging document was developed. The separation of operations was problematic because there were operations carried out by both OceanGate and Horizon Maritime Services Ltd. that involved the other group. The Polar Prince’s SMS was certified under the International Safety Management (ISM) Code, but there was no other external oversight of procedures for OceanGate and Horizon Maritime Services Ltd operations. 

The agreement to treat the Polar Prince’s operations as separate from those of OceanGate left the master of the Polar Prince in a conflicted position. This was because, on the one hand, the master was to treat OceanGate and its personnel as completely separate, but on the other hand, he retained the responsibility for the safety of all crew and passengers associated with the vessel. As well, the Titan could not operate independently from the Polar Prince; for communication, tracking, and other activities, the Titan was entirely dependent on the Polar Prince. 

When groups work on board a Canadian vessel or a vessel to which the Coasting Trade ActGovernment of Canada, Coasting Trade Act (S.C. 1992, c. 31). applies and they do not have comprehensive guidance from a bridging document to integrate safety management between their operations and those of the vessel, there is a risk that operations will be conducted without the necessary safeguards. The Board therefore recommends that