Trestle Bay is a shallow artificial reef located on the river side of the South Jetty near Astoria. The site features the remains of old wooden railroad trestles, which provide the primary structure for exploration. Divers and snorkellers can expect depths ranging from 1 to 5 metres, with an average depth of 4 metres. Access is possible from both shore and boat, situated 450 metres from the coast. Conditions at this site include moderate currents, low visibility, and potential entanglement hazards. Due to the shallow nature and environmental conditions, this site is suited for intermediate divers. Water temperatures fluctuate between 8C and 15C throughout the year.

South Jetty, located near Fort Stevens, provides access to a rocky reef and artificial reef ecosystem within the Columbia River estuary. This site is suitable only for advanced divers due to challenging conditions, including strong currents, surf, and heavy boat traffic. Visibility is generally low, ranging from 5 to 10 metres. Divers typically experience depths between 5 and 20 metres, with an average depth of 12 metres. Shore entry is required, and dives are typically 45 minutes in duration. Water temperatures remain cold throughout the year, fluctuating between 9 and 12 degrees Celsius. Due to the high-risk environment, this site should only be attempted during slack tide.

Cullaby Lake, located south of Warrenton, is a freshwater site suitable for beginner snorkellers. The lake features a designated swimming area, with the most productive areas for observation found near the docks and lily pads. Depths range from the surface to 9 metres, with an average of 4 metres. Conditions are generally mild, though water temperatures fluctuate significantly, ranging from 7°C in April to 20.5°C in July. Shore access is available, supported by facilities including parking, toilets, showers, and a rinse station. Snorkellers should remain aware of potential hazards, including boat traffic, cold water, and entanglement in aquatic vegetation.

The Silvia de Grasse is a shallow wreck site located off the Oregon Coast, United States. Resting at depths between 2 and 7 metres, the wreck requires boat access. Divers should be prepared for strong currents and limited visibility of approximately 5 metres, necessitating close proximity to the structure throughout the dive. Due to the variable conditions and current strength, this site is suited for intermediate divers with solid buoyancy control. Species recorded around this area include California sea lions, Steller sea lions, harbour seals, sea nettles, Pacific Lion's Mane jellyfish, rock crabs, and various snails. A drysuit or thick wetsuit with hood and gloves is recommended given the water temperatures of 8 to 15 degrees Celsius.

Gearhart Beach features an expansive sandy shoreline where snorkelers may explore shallow troughs located between sandbars. This site is best accessed during rare calm summer days when conditions allow for entry beyond the breakers. The water temperature at this location ranges from 8C to 15C throughout the year, requiring appropriate thermal protection. Due to the presence of surf and cold water, this site is rated for intermediate snorkelers. Shore access is available, with parking and toilet facilities provided nearby. Snorkeling activity is limited by the dynamic coastal environment, and visitors should exercise caution regarding local surf conditions.

Youngs River Falls is a freshwater site located south of Astoria, featuring a deep pool at the base of a 54-foot waterfall. Snorkellers can explore the rocky bottom of the pool, which offers visibility ranging from 1 to 5 metres. The site is accessed from the shore, with a typical session lasting around 120 minutes. Conditions are variable, with water temperatures ranging from 8C to 15C and moderate currents present. Due to the cold water temperatures and potential for currents, this site is best suited for prepared beginners. Parking is available for visitors at the site.

Painted Rock Beach is a shore-entry site featuring small rocky clusters that can be explored with a mask during flat ocean conditions. The site is shallow, with depths ranging from 1 to 5 metres and an average of 3 metres. Snorkellers may encounter common species such as sea nettles, ochre sea stars, rock crabs, and various snails. Less frequently, skates, Pacific lion's mane jellyfish, common moon jellyfish, opalescent inshore squid, and righteye flounder are recorded. Due to the cold water temperatures and potential for surf, surge, and rip currents, this site is best suited for beginners under calm conditions. Facilities include parking and toilets.

The Cove is a rocky reef site located three miles south of Gearhart. The topography consists of basalt boulders and tide pools, offering a shore entry for snorkelers. Depths range from 2 to 15 metres, with an average of 8 metres. Conditions are variable, with visibility typically between 5 and 15 metres depending on swell. Due to the presence of surf and surge, this site is suited for advanced snorkelers. Water temperatures fluctuate between 8C and 15C throughout the year. Facilities at the site include parking, toilets, and showers. Typical snorkel sessions last approximately 30 minutes.