About 216 miles or 3 hours 45 minutes

Starting in central Seattle take HWY 5 heading south for 126 miles
Turn right on HWY 432 heading west for 3 miles
Continue on HWY 433 heading southwest for roughly 2 miles
Turn right on HWY 30 heading west for 46 miles
Continue on US 101 (US 26) heading south for 37 miles to Nehalem, OR

local vicinity map