An expert submariner from the British Royal Navy, a team of French specialists on remotely operated vehicles (ROVs) and more ships and underwater vessels were joining the search, said Capt. Jamie Frederick, the First Coast Guard District response coordinator, in a news conference Wednesday afternoon.

The search was growing "exponentially" across a surface area roughly two times the size of Connecticut and 2.5 miles deep, he said.

"There is an enormous complexity associated with this case, due to the location being so far offshore and the coordination between multiple agencies and nations," Frederick said.