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Map of Keystone Jetty (Fort Casey Underwater Park)
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IntermediateShore entry

Keystone Jetty (Fort Casey Underwater Park)

Washington, United States
Open Water suggested3–18 m depthShore entry7mm or semi-dry + hood typical

Keystone Jetty (Fort Casey Underwater Park) at a glance

Keystone Jetty (Fort Casey Underwater Park) is a intermediate shore dive site in Washington, United States with depths of 3–18.3 m (10–60 ft). Typically most favorable Jul · from 3 years of archive data. Divers commonly see Wolf eel, Giant Pacific octopus, and Lingcod. Recent reports put the water around 16°C (62°F). Check the latest conditions and entry details before you go.

Marine model · graded 4h ago
0.1 mwaves — under half a meter expected

Tap a factor for its source and model point · Forecast 16°C · seasonal avg 14°C

Site hazards: Strong Admiralty Inlet currents outside slack, active ferry traffic on the far side of the jetty, bull kelp entanglement in season, exposed conditions in wind

Read the full hazards ↓

Dive windows this week

Best: Sun
Sun6:00–21:00
Mon6:00–21:00
Tue6:00–21:00
Wed6:00–21:00
Thu6:00–21:00
Fri6:00–21:00
Sat—

Favorable windowModerate window— no window

First light 5:01 · Sunrise 5:39 · Sunset 20:55

Source: Open-Meteo marine · model point 6.0 km from site · graded 4h ago

Forecast only — always assess conditions on site.

Forecast · NOAA tide model

Tide & slack timing

Loading tide predictions

Recent diver reports

Dated firsthand observations from divers — not current conditions.

No diver reports for this site yet. — one dated observation helps every diver after you.

What Divers Say

Known for: Wolf eel, Giant Pacific octopus, Lingcod
Best time: Slack water on small exchanges; summer has kelp and the most fish, winter the best visibility

Based on community reviews and site data. Conditions vary — always verify before diving.

Best months, historically

What conditions have historically been typical at this site, month by month — not a forecast.

  1. Jan95%8°C0.2 m
  2. Feb80%8°C0.3 m
  3. Mar88%8°C0.3 m
  4. Apr91%9°C0.3 m
  5. May99%11°C0.2 m
  6. Jun98%12°C0.2 m
  7. Jul100%14°C0.2 m
  8. Aug99%14°C0.2 m
  9. Sep99%13°C0.1 m
  10. Oct92%11°C0.2 m
  11. Nov81%10°C0.3 m
  12. Dec78%10°C0.3 m

July hastypically had the largest share of favorable days here. Conditions vary year to year — this is historical context, not a forecast.

Based on 3 years of archive data. Bar height shows the share of days each month whose conditions have historically scored favorably.

Marine life seen at this site

Species noted at this site — not a promise of what you’ll encounter.

Species seen here

  • Wolf eelCommonly seen
  • Giant Pacific octopusCommonly seen
  • LingcodCommonly seen
  • RockfishCommonly seen
  • NudibranchCommonly seen
  • Plumose anemoneCommonly seen
  • Bull kelpSeasonal
  • Striped seaperchCommonly seen

Fills & rentals nearby

No dive shops mapped within 25 km. Know one? Add it to the map.

Site details

Washington's other underwater state park, along the rock jetty protecting Keystone Harbor at Fort Casey State Park on Whidbey Island, next to the Coupeville-Port Townsend ferry landing. The jetty boulders are plastered with anemones and nudibranchs and shelter wolf eels, octopus and big lingcod, with about 55-60 ft of depth at the jetty tip. Admiralty Inlet currents sweep the site hard, so it is strictly a slack-water dive planned with Admiralty Head current predictions, and divers must never round the jetty into the active ferry lane.

reefshorewall

Strong Admiralty Inlet currents outside slack, active ferry traffic on the far side of the jetty, bull kelp entanglement in season, exposed conditions in wind

Reviews

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