Gale-force winds and high tides caused by Hurricane Dennis battered the fragile shoreline of this barrier island today for the second day in a row, sending sea water spilling over the dunes and stealing more sand from a beach that has little to spare.

Dozens of campers were evacuated today as the park flooded in places and drifts of sand blocked roadways at this popular recreation area eight miles south of Ocean City. The beaches and nature areas were closed as well, as rangers tried to assess where Dennis was headed and how much punch it had left.

Dennis, downgraded to a tropical storm with maximum winds of 70 miles per hour late tonight, had stalled over the open Atlantic and started moving toward the shoreline late this afternoon. By 11 p.m., it was about 105 miles east of Cape Hatteras, N.C. The winds were still strong enough to batter coastal resorts, and meteorologists warned that it could regain hurricane strength.

"You can't write it off yet," said Clay Stamp, Ocean City's director of emergency management.

The hurricane-tossed surf lapped at the boardwalk in Rehoboth Beach, Del. About 20 miles south, three areas in Ocean City--at 33rd, 81st and 146th streets--flooded during high tide on Monday night and again today.

But Terry McGean, Ocean City's engineer, said that overall damage to the beaches in his town appeared to be minimal--so far.

"It's tough to say how much of a problem we're going to have," McGean said. "A lot of the sand does come back. But if the wind keeps blowing and we get this wave action for four or five more days, that causes problems."

The situation was more volatile in Assateague Island, which has never completely recovered from a series of winter northeasters in early 1998 that washed away a section of the island. The island flooded again last winter, and at one point, nearly 95 percent of the dunes were wiped out along the state park's two miles of shoreline, said Ken Layman, a park ranger.

"We're taking a beating," Layman said today, as he toured the park's campground in his truck.

Park officials started to turn away new campers on Monday afternoon before evacuating the dozen or so who remained in the park. The 350 sites at the campground are usually filled this time of year. It looked like a ghost town today. At least one tent was buried in sand, with nothing but its triangular top visible.

After spending a harrowing night in their pop-up camper, two Baltimore residents didn't have to be told to evacuate. Marie Gillan and Connie Kertell said the wind Monday night was strong enough to blow a picnic table into their camper.

"I sat up all night and watched the ocean, hoping it would stay where it was," Gillan said. "The awning was banging. We were so afraid the top of the camper was going to collapse."

Terri Thompson, of Woodbridge, also spent the night in her camper, as it rocked back and forth in the wind. "The sand was just blowing everywhere," she said.

Ocean City officials said an anti-erosion program was helping to limit the damage to their resort town. The town has spent $74 million in federal and state funds since 1989 to replace beach sand lost to erosion. In all, 9.5 million cubic yards of sand have been pumped onto land between the inlet and the Delaware border.

"People look out and see all the water and they think the beach is gone. It's been redistributed, but in most cases, it's still there," said Ocean City Council member Nancy Howard.

But Howard said a northeaster, which produces conditions similar to what the Maryland and Delaware coasts have been experiencing this week, can cause more damage than a hurricane. That's because a northeaster hovers, and when it does, the high tides continue to take sand from the beaches without giving them time to recover.

Most beach areas on the Delaware and Maryland coasts were open today, although swimming was still prohibited. That didn't stop some people from trying. Ocean City police said they had to pluck about 52 people from the ocean on Monday night after they were caught trying to wade or swim in the rough surf.

CAPTION: Rob and Libby Alesbury and daughter Holly, 4, of the District, brave winds kicked up by Dennis while visiting Assateague.

CAPTION: Kaitlyn Coogan, 9, of Freehold, N.J., Kelly Gable, 9, of Warrenton, and Corinne Coogan, 6, of Freehold, move supplies to their grandparents' car to leave Assateague.

CAPTION: Marci Germann, of Freehold, N.J., packs up her camper at Maryland's Assateague State Park, which was evacuated in the face of Dennis. She said of the wind-blown sand, "It is murder."