Mysterious tar balls washed up on several Florida beaches, forcing closures and triggering an investigation by the U.S. Coast Guard. Fort Lauderdale’s shoreline was among the most impacted, after the strange oil slicks shut down swimming.

Most of Fort Lauderdale’s beach was shut down to swimmers during a busy beach day Saturday due to oil washing ashore.

LAUDERDALE-BY-THE-SEA - Oily tar balls have been washing up along South Florida beaches, stretching from Fort Lauderdale to Lake Worth Beach in Palm Beach County, raising environmental concerns and frustrating beachgoers.

The U.S. Coast Guard is investigating the source of a sticky black substance washing up on some Florida beaches.

A popular vacation destination closed its beaches after the discovery of mysterious tar balls on the shore, the origin of which is still unknown. Some theories indicate that they came from a nearby oi