A lily-pond treat along Silver Lake Wetland Haven Trail

Location: Castle Rock.

Length: One-mile loop, with several miles of trails across Highway 504 in Seaquest State Park.

Level of difficulty: Level, fine gravel trail with boardwalks (considered accessible to the disabled).

Setting: If you've ever taken summer visitors down to the Mount St. Helens Visitor Center five miles off Interstate 5, you may have noticed a ramp to a trail to the left of the main entrance. After several visits, I finally took the trail and discovered a place with almost as many natural wonders as the interpretive displays in the visitor center.

The trail starts off through a mossy conifer forest (with lots of yew trees), leading to a boardwalk that extends far out over a yellow pond lily-dotted marsh at the western end of Silver Lake. Eventually, you step off the boardwalk onto a long, low strip of land. An interpretive sign with an old photo describes how timber logging in the area during the early 1900s prompted the building of a railroad grade to transport the logs — which is now the skinny island you're standing on.

Highlights: Even non-birders may feel like sitting and watching for a while way out here on the water in the middle of the vegetated island. Thousands of migratory birds pass through here — and with thickets of willows and spirea forming a natural blind on either side of you, you'd have a hidden front-row seat for as long as you wanted.

As a former geologist, I was even more interested in the origin of the lake. About 2,500 years ago, Mount St. Helens erupted, sending landslides off the north side of the mountain, which blocked local streams and formed lakes behind the dams. Several lakes overflowed, sending huge mudflows roaring down the Toutle River with enough debris to dam nearby Outlet Creek and create shallow Silver Lake. To complete the trail loop, cross from the island over one more boardwalk; in the middle of the span is a touching memorial plaque to the 57 people who died in the 1980 eruption.

Facilities: Restrooms and water outside visitor center and across the highway at the state park campground.

Restrictions: Leash and scoop laws in effect; remember, bringing pets means you'll see less wildlife.

Directions: From Interstate 5 in Castle Rock, take Exit 49 and head east on Highway 504. In about five miles, turn right into the Mount St. Helens Visitor Center.

For more information: 360-274-0962 (visitor center) or see http://vulcan.wr.usgs.gov/Volcanoes/MSH/NatMonument/PointsInterest/silver_lake.html.