(CNN) A possible clue has surfaced on Day 3 of the search for two firefighters who disappeared after setting out from Port Canaveral, Florida, on a fishing trip.

A gear bag was found floating in the ocean Monday about 50 miles east of Jacksonville, according to the Coast Guard. The wife of Brian McCluney, one of the missing men, said on Facebook that the bag belonged to him.

"I wholeheartedly believe this is a bread crumb they [threw] overboard to say, 'We are here, come find us,'" Stephanie McCluney posted

Authorities say they have searched an estimated 24,000 square miles of ocean for the men.

McCluney and Justin Walker were last seen Friday morning on surveillance video launching their boat into the water at the 300 Christopher Columbus boat ramp, according to the Coast Guard . Their destination was 8A Reef, an offshore fishing spot, the Coast Guard said.