Don’t be surprised if you spot a sub

Watch for naval exercises off Fort Lauderdale.

A naval exercise is being held off Fort Lauderdale this week, in an area used for years to test submarines and surface warships.

The Coast Guard has declared a four-mile-wide security zone just south of the inlet into Port Everglades, barring any vessels from entering the area without permission, according to a notice that was published in Wednesday’s Federal Register, the daily chronicle of major actions by the federal government.

The Coast Guard declined to release details, but the exercise is taking place around an undersea testing range operated by the Naval Surface Warfare Center Carderock Division’s South Florida Ocean Measurement Facility.

The network of electromagnetic and acoustic sensors is used to evaluate submarines, surface ships and remotely operated vehicles, as well as accommodate mine detection and countermeasure testing.

The security zone starts three-fourths of a mile off the beach, giving room for smaller vessels to pass by the landward side. The zone lasts from5 a.m. to 8 p.m. through today.

“The security zone is needed to protect personnel, vessels, and the surrounding waterway from terrorist acts, sabotage or other subversive

acts, accidents, or other causes of a similar (nature) ” states the notice from the Coast Guard. “Entry of vessels or persons into this zone is prohibited unless specifically authorized by the Captain of the Port Miami.”

Although the notice just came out, it states that the security zone was established July 8. Thenotice states that the Coast Guard did not receive notice of the exercise until two days before it was to begin and said therewas “animmediate need to protect the security of the naval vessels.”

The Navy has not yet responded to a request for information about the exercise.

The South Florida OceanMeasurement Facility’s headquarters stands on the south side of the Port Everglades inlet, off a testing range the Navy has operated for more than 50 years. Boaters in the area occasionally glimpse a periscope or the top of a partially surfaced submarine.