It's the stuff of legends: When the "big one" finally strikes California, it is going to shake the state loose and send it crashing into the Pacific Ocean. The myth even made a top hit for the band Shango, whose "Day After Day" advised locals to "get ready to tie up the boat in Idaho."

The truth is not far off. Parts of California is indeed slipping away, but the culprit is not earthquakes but rising sea levels. Consider:

• In Oceanside, many vacation homes that used to advertise their "beachfront" location have changed the description to "oceanfront" because there is no longer any beach. An extensive rock wall has prevented these homes from slipping away, but the clock is ticking.

• At Capistrano Beach, officials are trying to rescue the eroding boardwalk with a rock wall.

• In Pacifica, cliffside homes are either cracking and crumbling, or disappearing completely into the ocean. In one particularly vulnerable section of coastline, 90 feet of bluffs have crumbled over the last ten years.

The real estate challenges created by rising tides are not limited to California. Every coastline in every state is or will be confronted by erosion, causing seismic shifts in real estate locations and investments.

In some areas, the problem may be insurmountable. Reliable projections indicate a sea level rise of 10 feet in South Florida by the turn of the century. Even if these scientists are 90% wrong, the additional foot of sea level rise would make 15 percent of Miami uninhabitable.

Rising tides are claiming large chunks of Louisiana which is losing the equivalent of a football field of land every 90 minutes.

In North Carolina, an award-winning professor emeritus of geology said last year of the state's coastline, "These beaches are doomed. The buildings are doomed, too.:

From town to town, there is disagreement on how to confront the crisis. Some locals believe that the best offense is a good defense and support the construction of sea walls to stop the erosion.

Others believe that "managed retreat" is the best option, that being an effort to abandon existing real estate development and let the ocean do its worst, or move the homes and businesses to new locations farther from the potential for damage.

Californians won't have to think about tying up the boat in Idaho, but property owners along the coast may want to start considering their options now.