The Arran Coastal Way offers walkers a challenging and rewarding 65-mile / 105 kilometre circular route around the beautiful Isle of Arran.  One of Scotland's Great Trails.  

http://www.coastalway.co.uk

From Seattle (Golden Gardens Bathhouse) to Everett (Pigeon Creek TH). The 26 mile route stays to the west of the railroad tracks and only leaves the beach for short sections in Edmonds and Mukilteo, and then finishes on a short paved trail in Everett.

The challenge of this route is twofold: limited route existence due to tides and the ever-changing terrain of sand, sharp or slippery rocks, and some boulders.

Over 1200 miles from the Pacific Ocean in Washington to the Continental Divide in Montana, the Pacific Northwest National Scenic Trail travels through diverse ecosystems. Being one of the youngest National Trails, it can be quite rugged and challenging. The trails traverses three National Parks: Olympic, North Cascade, and Glacier; as well as seven national forests. Rainforest to high desert, ocean to alpine; this trail travels through many gems of the upper left corner of the U.S. 

The Sussex Border Path is a 141 mile routet hat follows the entire border of East and West Sussex from Rye to Thorney Island.