Driving from Seattle to Seabrook offers a serene and scenic journey spanning roughly 2½ to 3 hours along 130–150 miles via I‑5, US‑12, US‑101, and finally SR‑109 — also known as the Hidden Coast Scenic Byway.After departing Seattle, you head southwest through charming rural towns before connecting to US‑101, which leads west onto the coast. Turning onto SR‑109 lets you cruise the “Hidden Coast,” where dramatic Pacific bluffs, wide sandy beaches, and forested dunes unfold, with frequent pull‑outs ideal for beach walks, bird-watching, and exploring spots like the Copalis Ghost Forest.