Seaside's beach is wide, flat, and dark-sand — the volcanic origin of the Pacific Northwest coast gives Oregon beaches their characteristic grey color rather than the white quartz sand of the Atlantic coast. The beach runs for several miles in each direction and at low tide the flat wet sand extends a long way out, making it ideal for running, cycling (permitted on the hard-packed lower beach), and the kind of long, mindless walking that the Oregon coast does best.
The water is cold year-round — summer temperatures peak around 55°F (13°C) — and swimming without a wetsuit is possible but brief. Surfing is consistent here, particularly in fall and winter when the swells pick up; Seaside has a genuine surf culture and hosts the US Open of Surfing's Pro Junior competition. Bonfires are permitted in designated areas on the beach, which makes summer evenings when the marine layer lifts genuinely atmospheric. Razor clamming is open in season, check the Oregon Department of Fish and Wildlife's website for current dates and conditions before you go.