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Back  |  USA: Pacific Northwest   |  Puget Sound - South

Tacoma Narrows Bridge - Caissons  |  USA: Pacific Northwest

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Tacoma Narrows Bridge Pylons
Tacoma, WA

Type: Saltwater
Advanced, Technical

Ratings (1-5):
Reviews: 2
Enjoyment: 4
Visibility: 4.5
Current: 3.5
Aquatic Life: 5

Photo Gallery:

Diver on the Tacoma Narrows Bridge
Ostrich Plume Hydroid
Metridium Anemones
Scalyhead Sculpin
Small Nudibranchs
Red Irish Lord
Mature Male Scaly Head Sculpin


Caissons (Pylons) holding up the Tacoma Narrows Bridge Structures,


The pylons that support the Tacoma Narrows Bridge (called caissons) are cement monstrosities that plummet to into the intensely current swept passage between Tacoma and Gig Harbor. The are impressive structures above the water, and the submerged portion is simply a thrilling dive site.

First off, there are now two bridges - the old bridge to the north and the new bridge to the south. Each one has a supporting caisson on the east end and the west end, making four different possible caisson dives. They vary in depth from 110' deep on the side caissons nearest shore to 140+ on the inside of the caissons. Double check with a depth finder to verify the depth of your descent point.

The caissons on the Old Tacoma Narrows bridge are octagonal so it may seem as though you have swam around it and in actuality be far from it. They are covered with very large barnacles which provide shelter to a wide array of small sea-life including nudibranchs, cucumbers, anemones, and many varieties of sculpin, gunnels and pricklebacks. You may also find perch schooling and rockfish near the base. Drop in near the shore side on the West end and it is only about 110' deep to the bottom, providing a sense of security upon your descent.

The new bridge (south) provides the above listed visuals but with an additional dense population of colorful metridium which have taken hold of the newer concrete walls. They also have a large assortment of life on them and the two sets look very different from one another.

The top 20-25' of each caisson has many varieties of kelp, dense in some spots and a large portion of mussels. The bottom is covered in large barnacle encrusted rocks and debris that sank during the construction of the bridges. The most colorful and interesting portions of all of them are the top 50' or shallower so there is no need to spend an incredible amount of time at depth nor entering into deco on a potentially hazardous dive site.

Special Restrictions:

Where to begin... This is an advanced dive for numerous reasons and should not be attempted by anyone without the proper training and experience.

  • This site is VERY current sensitive and a live boat is mandatory. Pick a minimal exchange day and dive at slack in the lee of one of the caissons.
  • DEEP water and sheer drop to 100 feet or more so buoyancy control is also mandatory.
  • There is some kelp near the surface so beware of that too.
  • Heavy boat traffic through the narrows (including fishing boats) so stay close to the caissons.
  • Make sure to cary a visual signaling device in case you get swept off the caissons in the current. Audio ones are good too but there is a lot of noise here from fog horns, vehicle and boat traffic, your own live boat's motor, etc.
  • Use a compass - the old bridge has octagonal caissons and currents are irregular on all four, often shifting directions at various depths and sides making it easy to get disoriented to what side of the caisson you are on.

How to get there:

Easy to find - navigate toward the Tacoma Narrows between Tacoma and Gig Harbor and look for the double HWY 16 bridge running high over your head. There are four caissons on the bridge. The old bridge is to the north and the new bridge to the south.

Thanks to ChevaYEA for submitting this site!
  Comments Leave Review  
ChevaYEA4/18/2009Rating: 4
This is a sweet dive! I'm glad I can say I've been to the bottom but next time I'll stay in the top half of the caissons where the majority of the life is. It was easier to stay out of the current in the eddies of the caissons than I thought it would be - but then we had a very small exchange and were diving at slack. We did both the new bridge and the old bridge caissons on the west side and I can't wait to do it again.

Chris4/18/2009Rating: 4
This dive was fun. The top 50' is the best as far as the life goes. Plan this dive very carefully as it could be a hazardous location.


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