The Historic Seaside Promenade (known as the Prom) is one and a half miles long, stretching from Avenue U (on the south end of town) to 12th Avenue (on the north end of town), and of course it borders along the gorgeous Pacific Ocean. Taking a stroll along the Prom is an absolute must whether you’re just passing through Seaside, or staying for a few days to enjoy all Seaside has to offer. It is a 15-foot wide paved walkway that was built in 1920, and dedicated in 1921 (prior to that there was a wooden walkway).