Angle Lake Beach is the swimming beach at Angle Lake Park, a ten-acre waterfront park owned and run by the City of SeaTac Parks, Community Programs and Services department. The park sits at 19408 International Boulevard and occupies the western shore of Angle Lake, a 102-acre glacial lake between Interstate 5 and State Route 99 in southern King County. The lake is named for its shape, an L with a sharp right-angle bend.

The swim area is a groomed sand beach about 80 meters long, tucked into the southeast corner of the park where the lawn drops to the water. Entry is gradual and sandy and a buoy line marks the outer edge of the guarded area. King County puts the lake at 102 acres with a mean depth of 25 feet and a maximum of 52 feet, though none of that depth is near the beach. A floating dock sits just south of the swim area, keeping swimmers clear of the fishing crowd.

Lifeguards work the beach in summer, generally daily from noon to 8 p.m. The opening and closing dates move year to year and the city says the schedule is subject to change, so call the SeaTac Community Center at 206-973-4680 before planning around guarded hours. Outside those hours nobody is watching the water. The park is open dawn to dusk and the vehicle gate is unlocked by 8 a.m. There is no entry or parking fee. Reserving a picnic shelter does cost money, and summer weekend dates book out early.

Water quality here is actually tested, which is unusual for a city beach. King County's Department of Natural Resources and Parks samples Angle Lake Beach weekly from mid-May through late September, pulling three samples from different parts of the beach and testing for fecal bacteria and toxic algae. The beach was added to the program only recently, so it does not yet appear in the county's multi-year historical rankings. Results post to the county site and to Swim Guide within a few days. The county's small lakes program has rated Angle Lake oligotrophic, meaning low in nutrients and algae, every year since 2008, on a watershed of just 478 acres.

Check conditions before you go, because the shoreline is a construction zone. The 50-plus-year-old floating dock and boat ramp failed and the ramp has been closed. The replacement reached 90 percent design in 2026 and adds an elevated fishing pier set farther from the swim area, a rebuilt precast concrete ramp, a kayak launch, new stairs and handrails down to the sand, and an ADA ramp into the water at the north end of the swim area. Expect fencing, noise and shifted access while that work runs.

Two more things worth knowing. The runway ends at Seattle-Tacoma International Airport are less than a mile west, so jet noise is constant rather than occasional. And in April 2026 the city council approved a pilot program allowing up to three exclusive-use permits a year that let a group close the whole park to the public for an event, so a summer weekend visit is not guaranteed.

The site was a private lake resort in the 1920s. King County bought it in 1957 and later transferred it to SeaTac.