The scenery of rocky headlands, ravines, waterfalls and towering cliffs gained the Exmoor coast recognition as a heritage coast in 1991. With its huge waterfalls and caves, this dramatic coastline has become an adventure playground for both climbers and explorers. The cliffs provide one of the longest and most isolated seacliff traverses in the UK. The South West Coast Path, at the longest National Trail in England and Wales, starts at Minehead and runs along all of Exmoor's coast. There are small harbours at Lynmouth, Porlock Weir and Combe Martin. Once crucial to coastal trade, the harbours are now primarily used for pleasure; individually owned sailing boats and non-commercial fishing boats are often found in the harbours. The Valley of Rocks beyond Lynton is a deep dry valley that runs parallel to the nearby sea and is capped on the seaward side by large rocks, and Sexton's Burrows forms a natural breakwater to the harbour of Watermouth Bay on the coast.