They also provide rest stops for sea lions, elephant seals, and harbor seals. Vegetation in the Sanctuary varies considerably depending on the size and shape of the rocks and islands. The smaller, pointed rocks have little or no vegetation, while the larger, flatter islands have an extensive cover of grasses, herbaceous plants, shrubs and conifers. The islands and rocks have weathered to varying shapes and sizes. Some of them have pools of rainwater that accumulate during the rainy season, but otherwise fresh water is not available on these islands.
Most rainfall occurs during the winter months.
Summers days are generally warm with cool nights. Ocean breezes and early morning fog are also common during the summer. Most of the rocks and islands are not readily accessible. Consequently, their associated biological communities are relatively undisturbed. Some of the sites, however, are accessible by wading, swimming, or boat.