It is presumed that the object in question was brought from Cuban waters to Florida by Irma, the Hurricane.

From here:

A 1,200-pound Soviet buoy that surfaced off Dania Beach looks like it belongs in a James Bond movie. Script — which the Library of Congress says is Russian for Hydrometrical Service of the USSR — is painted in black on its side.

Exactly where the rusty, Cold War-era relic came from, and what it was used for, remain a mystery.

Workers at Dr. Von D. Mizell-Eula Johnson State Park pulled it off the beach just days after Hurricane Irma swept through town. They think it floated 350 miles from Cuba, given Cuba’s historically close ties with the Soviet Union.

Bill Moore, the park’s maintenance mechanic, locked eyes on the 12-foot buoy at the same time Coast Guard members did. He marveled at it, thinking, “You don’t find that too often.”

The Coast Guard’s administrative offices are next to the park’s headquarters. “They came running down here with their dog,” he said. “They tried to confiscate it.”

But Moore retrieved it before the Coast Guard could, he said. The buoy was too heavy to budge, so Moore tied a rope around it and with a skid-steer loader dragged it up the embankment and then brought it to the park office’s parking lot.