From an AP story by Ben Finley and Holly Ramer headlined “Deep-sea craft carrying 5 people to Titanic wreckage missing, search underway”:

A rescue operation is underway deep in the waters of the Atlantic Ocean on Monday in search of a technologically advanced submersible vessel carrying five people to document the wreckage of the Titanic, the iconic ocean liner that sank more than a century ago.

The vessel was reported overdue Sunday night about 435 miles (700 kilometres) south of St. John’s, Newfoundland, according to Canada’s Joint Rescue Coordination Centre in Halifax, Nova Scotia. Lt. Cmdr. Len Hickey said a Canadian Coast Guard vessel and military aircraft were assisting the search effort, which was being led by the U.S. Coast Guard in Boston.