There are at least 5 ships operating in the area where the sound was heard (an underwater knock, the alleged crash site of the Titan submersible).
An important vessel is approaching that can provide significant assistance: HORIZON ARCTIC
On June 20, OceanGate Expeditions confirmed that its bathyscaphe with five tourists disappeared while diving to the Titanic that sank in the Atlantic.
upd: + research vessel ATALANTE (perhaps also able to help) + Terry Fox
An important vessel is approaching that can provide significant assistance: HORIZON ARCTIC
On June 20, OceanGate Expeditions confirmed that its bathyscaphe with five tourists disappeared while diving to the Titanic that sank in the Atlantic.
upd: + research vessel ATALANTE (perhaps also able to help) + Terry Fox