BNRR has put a fence along the rail road which prevents shore access for divers and pedestrians.  This site can be accessed by boat. (Brian Heath 08-2011)

Dive Site Description:

The rock is a nice divesite. It's always a great place to find a grunt sculpin or a mossy-headed warbonnet. 100' Rock features MODERATE ACCESS and a short swim. I call it moderate access, it requires a 300 yard hike down the railroad tracks and then descending a short staircase down to the water. No restroom or changing facilities are available near the divesite. This divesite is suitable for intermediate level and above divers. As the name implies, this is a deep dive.

Alternate dive site is just out in front of the pier. Tire piles and other stuff. This is rated intermediate because the entry requires rock climbing.

TEST YOUR DIVELIGHTS AND BRING THEM! Wearing a Glowstick, or the flashlight equivalent, is highly recommended.  (Yes it does get dark at 100ft.)
 
Directions:

It's located near the Meadowdale marina in Lynnwood. Just South of Meadowdale Park.

• Take Exit 179 on I-5 (220th St SW).
• Go west until you cross Highway 99, and take a right at the next light onto 76th Ave SW.
• Your goal is 162nd St SW, so follow 76th Ave SW for quite a while until you hit a 4-way stop. Continue straight through into a more residential looking area for about 1.3 miles.
• Take a left onto 162nd St SW. It curves down to the railroad track.
• Park on the side of the road overlooking the Meadowdale Marina.