The Coastal Lowlands ecoregion contains beaches, sand dunes and spits, and low marine terraces below 400 feet (122 m) elevation.

Characteristic features include wet forests, shallow freshwater lakes, estuarine marshes, and low-gradient, meandering tannic streams and rivers.

Mature forests in the region are dominated by a canopy of Sitka spruce, western hemlock, and Douglas-fir, with salal, sword fern, vine maple, and Oregon grape in the shrub layer.

The riparian zone supports red alder, western redcedar, and bigleaf maple with an understory of salmonberry; California bay-laurel is common in the south.

Estuaries and coastal wetlands may feature Baltic rush, Lyngby's sedge, tufted hairgrass, Pacific silverleaf, and seaside arrowgrass with shore pine, sweet gale, and Hooker's willow.

After extensive logging, most of the Sitka spruce is gone, and today the forests are dominated by Douglas-fir and western hemlock, with a shrub layer of salal, sword fern, vine maple, Oregon grape, rhododendron, and evergreen blueberry.

Wetter slopes and riparian areas feature red alder, bigleaf maple, and western redcedar, with a salmonberry and currant understory.

Mature forests consist of Douglas-fir, western hemlock, salal, sword fern, vine maple, Oregon grape, and rhododendron.

Wetter slopes and riparian areas may support western redcedar, bigleaf maple, red alder, salmonberry, and oxalis.

Grassy coastal headlands and mountaintop balds feature Roemer's fescue, thin bentgrass, California oatgrass, and diverse forbs.

The region lies outside the zone of marine influence, and its medium gradient streams and rivers have lower summer flow than most other parts of the Coast Range.

It is the smallest of the Coast Range subregions, covering 354 square miles (917 km2) in Grays Harbor County north of Aberdeen, Washington.

The vegetation consists of Douglas-fir and western hemlock forests, with sword fern, vine maple, salal, Oregon grape, and rhododendron shrub layer.

Wetter slopes and riparian areas support red alder, western redcedar, bigleaf maple, salmonberry, and oxalis.

[1][2] The mountainous Mid-Coastal Sedimentary ecoregion lies outside of the coastal fog zone and is typically underlain by massive beds of sandstone and siltstone.

The mature forest consists of Douglas-fir and western hemlock, with salal, sword fern, vine maple, Oregon grape, and rhododendron; tanoak may be found on drier slopes to the south.

Wetter slopes and riparian areas support bigleaf maple, western redcedar, grand fir, red alder, salmonberry, and oxalis, with California bay-laurel in the south.

Rising to an elevation of approximately 4,000 feet (1,219 m), this region has the climate of the Coast Range but the varied lithology of the higher, more dissected Siskiyou Mountains, underlain by Jurassic sandstone, metamorphosed sediments, granite, and serpentinite.

The region covers 692 square miles (1,792 km2) in a remote area of Curry County in southwestern Oregon containing the Sixes and Elk River drainages.

Historically, unbroken redwood forests occurred and moderated local climate by trapping coastal fog and producing shade.

The King Range thrusts 4,000 feet (1,200 m) above the Pacific, making this area one of the more spectacular and remote stretches of coastline in the continental United States.

In the northern part of the region, the Bear and Mattole Rivers drain a hilly-to-steep landscape of mixed evergreen forest, with a land cover that includes a relatively greater amount of annual grasslands than in Ecoregions 1i to the north or 1k to the south.

Vegetation includes a multi-story canopy of redwood, Douglas-fir, tanoak, bigleaf maple, evergreen shrubs, and various grasses.

Common vegetation includes Douglas-fir, tanoak, Bishop pine, coast live oak, Pacific reedgrass, and coyote brush.

[6] A small outlier of the region occurs in the south in Marin County that includes the coniferous and hardwood forests of Mount Tamalpais and Bolinas Ridge.

Various types of coniferous and hardwood forests occur, composed mostly of Douglas-fir, redwoods, tanoak, madrone, California bay, and coast live oak.

Mount Tamalpais and Bolinas Ridge force moisture out of the air as it cools and ascends the steep western mountain faces.

[6] The Santa Cruz Mountains ecoregion covers the western and southwestern parts of the range where vegetation includes redwood, Douglas-fir, tanoak, coast live oak, and California bay, along with some chaparral and coastal scrub species.