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Tides are the regular variations in sea level caused by the gravitational forces of the sun and the moon. The tides will reach a maximum and minimum depth each day, called high and low tide respectively. The tides vary seasonally with different maximum and minimum depths attained throughout the year.


Minus, or negative, tides occur when the tide level drops below the average low tide level. These are the best opportunities for viewing tide pools.

In Seattle the lowest tides occur during the summer months in daylight. During the winter months low tides typically occur in the middle of the night.

Crab in Crescent City tide pool

Tide pools are pockets of water left along the shoreline when the ocean water recedes during low tide.

They vary in size and may be many feet wide or merely a couple of inches. Organisms that live in tide pools must be adapted to endure extreme conditions when the ocean waters recede and they are left exposed to predators, sunlight, and temperature fluctuations.

High tides also present hazards to tide pool residents. Foraging fish gain access to the tide pools as the ocean rises.


Waves constantly batter tide pool organisms as the ebb and flow throughout the day.  To survive in these extremes, many tide pool residents have means by which to cling to rocky surfaces and hardened exteriors to deter predators.

A diverse array of organisms are represented in tide pools. Low tide presents an opportunity to view these creatures that are normally below the surface of the ocean. Sea stars, fish, sea urchins, crabs, sponges and anemones are all tide pool residents.


Each visit to the same tide pool can vary greatly. Over time the same tide pool may have fewer and fewer residents or not be visible at all due to sea level rise. Development along the seashores may also pose a threat to these diverse ecosystems.


Explore, treasure and share these habitats but also care for them as they may rapidly vanish if not managed appropriately

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