Sea caves are usually hollowed at the base of sea cliffs by the erosive force of water. Under the onslaught of waves, weaker sections of rock in a sea cliff erode more quickly than neighboring harder rock, and wave-cut nips and notches begin to form. Crashing waves may bear rocks or sediment, augmenting their scouring power. Wave action can also force open any dikes, faults, or fractures in sea cliffs, speeding up the erosive process. Sea caves are also found in headlands, as waves, refracted when they encounter the coast, sweep parallel to the land, and converge on prominent coastal features. Oregon’s Sea Lion Caves are among the Paciﬁc coast’s most popular destinations. Painted Cave, a 1,227-foot-long sea cave on Santa Cruz Island off the coast of California near Santa Barbara, is one of the world’s largest. Its name comes from the colorful lichens and algae that grow on the cave’s walls.