For eons, the island has drawn wildlife and humans to its soaring cliffs and white sandy beaches, with 360-degree vistas rising above the shimmer of the Magothy River.

But since sea level rise and erosion separated the spit of land from the mainland about 3,000 years ago, creating what is now known as Dobbins Island, it has continued to surrender to the effects of wind, waves and time.

Once recorded as being 18 acres, the island has eroded to less than eight acres, according to its owners, and each year several more feet slump into the river.

Anne Arundel County brothers Jim and Ed Wilson bought Dobbins several years ago as part of a parcel in Pasadena on the northern shore of the Magothy, which was their primary interest.

Never really sure what to do with the island, they tried persuading the state and county to buy it and use the island as a dump site for clean material dredged from the Magothy to keep it navigable for boaters. The Wilson brothers even offered to donate the property to a local land conservation group.

At first, it sounded like a good deal. But upon closer inspection, officials decided that it would be too costly to stop the erosion, and environmental laws would likely prevent its use as a dump site for dredge because underwater grasses have grown in the shallows around the island in recent years.

And then there was the problem of liability. In summertime, it is not uncommon to see hundreds of pleasure boats anchored offshore from the island while thrill-seekers -- adults and children alike -- swim ashore to picnic and explore.

"Anyone who's grown up in the Magothy watershed used the island, including my brother and I when we were in high school," owner Ed Wilson said. "It's always been an escape. Kids who played there when they were young bring their kids back there. It's a magical kind of place."

It was the irresistibility of the island that proved to be too much of a potential liability for the county or state, which bowed out of discussions.

So, with no clear plan for the land, the Wilsons last month put the island on the market for $1.75 million, marketing it in high-end publications to reach potential buyers, including helicopter owners.

Katherine Lundvall, a Realtor with the Annapolis Realty office of Christie's Great Estates, said the island is zoned for one house and has a parking spot on the mainland.

It's an investment opportunity, she said, that also could provide an appealing getaway spot for a boater.

"The person who purchases it will have to put some money into it in order to preserve it, but it could make an ideal private retreat with fabulous views," Lundvall said.

Indeed, people have been captivated by the allure of Dobbins Island for thousands of years. In the beginning, state historians say, it was home to Algonquin-speaking Native Americans who fished crabs and oysters from its waters and hunted turkey and deer on its shores. Then, as legend has it, pirates and privateers used it to stash their plunder. At one point, gold Dutch coins were found on its shores, lending it the name Dutch Ship Island for a time.

When John Smith sailed up the Chesapeake, the Indians would largely have left the area, driven off by tribal wars, so that settlers could easily have laid claim to the island. In 1769, it was surveyed and recorded as being 12 acres, and deeded to William Gambrell, according to author Marianne Taylor, who wrote a history of the Magothy called "My River Speaks." It became known as Dobbin Island in the late 1800s after the Dobbin family purchased it.

At various times in history, the island was used as a tobacco plantation and as a grazing area for livestock. Wayne Clark, chief of the office of museum services for the Maryland Department of Housing and Community Development, said settlers often used islands to contain their herds, rather than build fences around pastures.

"It's quite unique given what's around it," Clark said of the island. "It's a little slice of prehistoric Maryland in the middle of a suburban residential waterfront area and creates this wonderful feeling like you've stepped back in time. From an archaeological standpoint it's important because it's the last remnant of a former land surface, most of which is now underwater."

County archaeologist Al Luckenbach said the foundation of an early 20th-century home still exists on the island. But otherwise, few signs of human inhabitants remain. Today, the island is overrun by poison ivy and weeds, and the soaring cliffs are crumbling into the river.

Unfortunately, it's a problem that is occurring all along the western shore of the bay, according to scientists, making it all the more difficult for public officials to devote resources to just one private island.

Wilson estimates it would cost at least $1 million to build a jetty or other containment system to preserve the 4,000 feet of waterfront on the island.

"It's a unique, one-of-a-kind place, and when it's gone, that's it," Wilson said. "We can either sit back and watch it slowly disappear or find someone who can stop that from happening."

Sally Horner, executive coordinator for the Magothy River Land Trust, had tried to help the owners find a way to preserve the island, but the group eventually decided the liability risk was too high.

"It's been seen and used as a public spot for so long, you're going to have to have a guard to keep people off it," Horner said. "An opportunity is one way of looking at it. A headache is another."

Dobbins Island, a five-acre swell in the Magothy River, is for sale after owners couldn't arrange a deal to preserve it.