Big breakers chewed away at beaches and provided thrills for surfers, body-boarders and shoreline crowds.
In Venice Beach, a 27-year-old man was pulled from high surf in grave condition Thursday night, but paramedics were able to regain a pulse as he was taken to a hospital, Los Angeles fire spokesman Erik Scott said.
However, meteorologists said the conditions had peaked and would gradually subside through Friday, with high surf advisories expected to expire that evening.
Tropical Storm Marie, downgraded from hurricane status, was spinning more than 800 miles west of Punta Eugenia, Mexico, and was expected to be further downgraded to post-tropical cyclone status Thursday night, according to the U.S. National Hurricane Center.
The storm was moving toward the northwest at about 15 mph with maximum sustained winds dropping to 45 mph.
Surging surf arrived on the Southern California coast late Tuesday and was wildest on Wednesday. Blocks of oceanfront homes flooded in low-lying Seal Beach south of Los Angeles, pilings were knocked off the Malibu Pier and a boatyard on Santa Catalina Island was battered.
Warnings or advisories were posted for hundreds of miles of coastline. The National Weather Service called it the region's most significant southerly swell event since July of 1996.
Lifeguards worked to keep all but the most experienced surfers and swimmers out of the water but still made hundreds of rescues.
Beaches were left with deep gouges and abrupt drop-offs more typical of the aftermath of winter storms than summer.
At scenic Sycamore Cove below the rugged Santa Monica Mountains, waves on Thursday gradually stole remnants of an old lifeguard building known as the Cove House that collapsed into the angry surf overnight.
In Seal Beach, bulldozers were maintaining a high sand berm hastily created to protect shoreline homes and facilities, and the Port of Long Beach resumed operations at two cargo terminals where conditions a day earlier were too dangerous for the loading and unloading of four vessels.