The idea was to use a private blockchain to "promote more efficient and secure global trade" by allowing shipping companies to share information including shipping container contents and tracking. However, it was apparently tough to convince these companies to actually adopt the project, and Maersk and IBM pulled the plug.
Maersk and IBM announce the discontinuation of their blockchain-based TradeLens platform
Tough news for folks who insist that blockchains' obvious use case is for supply chains: IBM and Maersk have discontinued their private blockchain-based TradeLens platform due to lack of interest.