Coast

round, spiny purple and red urchins & orange frilly nudibranch in tidepool
Spiny purple and red sea urchins share a tide pool with the frilly orange feeding tentacles of a sea cucumber.

Olympic National Park's 73-mile long wilderness coast is a rare treasure in a country where much of the coastline is prime real estate. The rocky headlands, beaches, tidepools nurturing a living rainbow of colors and textures, off shore sea stacks topped by nesting seabirds and wind-sheared trees-all are a remnant of a wilder America. In fact, in 1988, Congress added much of the narrow coastal strip of the park (and much of the rest of the park) to a national system of designated wilderness.

Sharing Protection
The intertidal areas, where the Pacific Ocean tides shape life, are also within the boundary of the Olympic Coast National Marine Sanctuary. The offshore islands with their colonies of nesting seabirds and rocky haulouts for seals and sea lions, lie within the Washington Maritime National Wildlife Refuge Complex.

A Layer Cake of Life
Peer into a tidepool and your view may take in hundreds of animals crowded into an area the size of a dinner plate. Cold, nutrient-rich waters upwelling from the Pacific Ocean floor feed a food chain extending from tiny invertebrates to many-ton whales. In the intertidal zones, that abundance is stacked in layers determined by the tides, competition and the reach of predatory neighbors. Each species tends to thrive in only a certain narrow band of habitat, rarely straying above or below. Learn more about life in tidepools here.

This tidal layering is separated into four main zones: the Splash or Spray Zone, the High Tide Zone, the Mid Tide Zone, and the Low Tide Zone. These zones each see varying levels of water cover and exposure, which leads to a variety in both the animal and plantlife that can thrive within.

The Splash Zone, for example, earns its name from never being submerged under high tide. Rather, any moisture that coats the rocks in this area comes from the spray off of lapping waves. In this zone, one may find assorted mollusks such as limpets and other sea snails.

The High Tide Zone recieves water cover only during the height of high tide. Twice a day, depending on how far inland the tide moves, the animals of this zone may be submerged. However, they must be well-adapted for a life that sees much exposure to the elements of sun, wind, and the potential for predators. Shelled animals like barnacles and mussels latch onto the rocky surfaces.

The Mid Tide Zone, primarily reachable during low tide, provides viewers with a vibrance of color. More often bathed in tidal basins rather than out of water, colorful creatures like seastars, sea anemones, and the occasional crab find both shelter and food here.

The Low Tide Zone is fully submerged most times of the month. However, when the low tide is at its absolute lowest, a haven for sea urchins and nudibranchs appears.

Further out from the various tidal zones, the ocean comes alive with an assortment of
sea mammals, shorebirds, and pelagic (open-water) fishes. Look for the bobbing heads of harbor seals and sea otters. Bald eagles, cormorants, murres, and white and brown pelicans take flight overhead. Many fish both native to the salty waters and the temporary resident salmon are found along the many coasts.

 
The image depicts a rock on the Pacific Coast with small round holes left by piddock clams
Boulders on which piddock clams have left their mark can be seen along the Olympic coast

NPS Photo

The Dance of Life and Rock

A lumbering bear sleeps away the winter months in a warm den; with a whistle of warning, a marmot hurries underneath the talus of a scree slope; a mountain goat clings to life hundreds of feet in the air with nothing more than a knife's blade thinness to grip to. Throughout nature, animals have relied on natural rock formations for safe harbor, and the coastline is no different. Along Olympic's shores, a direct connection can be made between biology and geology--living organisms and solid stone.

Offshore islands provide both refuge and nesting grounds for birds like the common murre and the tufted puffin. Twice daily as the tide slinks back from the beach, water from the waves gets caught in natural rock basins amidst boulders. These temporary tidepools create a momentary metropolis for a variety of tidal life like seastars and anemones as they find both food and safety from the ocean's turbulence.

In some areas, the mark left by former beach residents can be seen. Along the coast, boulders that appear pockmarked and pitted perplex many that pass by. The guilty culprit of these holes comes in the form of a simple clam, known as the piddock, which bores into the rock to keep safe from scavengers.

 

"Working Between the Tides"
See science in action at Olympic National Park! Click HERE for this special video, part of the Science Minute Video series.

Pacific Ocean Newsletter
This newsletter is published quarterly by the Pacific Ocean Education Team (POET) of the National Park Service.

 
offshore islands in fog are beyond eroded arch in rock cliff in front
The eroded arch of Hole-in-the-Wall, north of Rialto Beach, with rocky islands and sea stacks beyond.

Last updated: September 28, 2020

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