The second-largest crane vessel in the world is currently stationed at the mouth of Halifax harbour — and it could be there for a while.

The Thialf made its Trans-Atlantic journey from Amsterdam to Nova Scotia last month so it can do the heavy lifting required to decommission the Sable offshore natural gas project.

But just when that will happen is up in the air due to concerns with COVID-19.

The vessel cannot begin work on the project until the Canada-Nova Scotia Offshore Petroleum Board issues an "operations authorization." Board spokesperson Laura Wright said it is currently reviewing the application for authorization.

The Sable offshore natural gas project began production in 1999. At the time, it was projected to have a lifespan of 25 years, but owner ExxonMobil announced in 2010 it would wind down Sable. Production ended in 2018.

Due to the COVID-19 crisis it's unclear how long Thialf will remain at the mouth of Halifax harbour. (Paul Palmeter/CBC)

ExxonMobil is overseeing Heerema Marine Contractors, out of the Netherlands, which will use the Thialf to remove the offshore platforms, the final stage in the Sable decommissioning.

A spokesperson for ExxonMobil said there are 130 workers currently on board Thialf.

"Our focus right now is the safety and health of the workforce, and to do our part to limit the spread of the novel coronavirus in the community," Merle MacIsaac said in an email.

MacIsaac said Heerema has a comprehensive plan in place to closely monitor, screen for and prevent exposure to the coronavirus.

In light of various travel restrictions and other guidance from authorities, Heerema is reviewing its plans and procedures to ensure the work is carried out safely if it gets permission to move forward.

"The schedule may be affected by these developments," he said.

The vessel is expected to have a total crew of 300 at any time when working on the Sable project. About half will be an international crew, said MacIsaac, with the remainder from Canada, including Nova Scotia.

The vessel is capable of housing more than 500 workers. If authorization is granted, all crew going aboard Thialf will have to complete a 14-day quarantine in advance of boarding.

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