The Pembrokeshire coastline includes numerous bays and sandy beaches. The Pembrokeshire Coast National Park, the only park in the UK established primarily because of its coastline, occupies more than a third of the county. The park contains the Pembrokeshire Coast Path, a near-continuous long-distance trail from Amroth, by the Carmarthenshire border in the southeast, to St Dogmaels just down the River Teifi estuary from Cardigan, Ceredigion, in the north. The National Trust owns of Pembrokeshire's coast. Nowhere in the county is more than from tidal water. The large estuary and natural harbour of Milford Haven cuts deep into the coast; this inlet is formed by the confluence of the Western Cleddau (which flows through Haverfordwest), the Eastern Cleddau, and rivers Cresswell and Carew. Since 1975, the estuary has been bridged by the Cleddau Bridge, a toll bridge carrying the A477 between Neyland and Pembroke Dock. Large bays are Newport Bay, Fishguard Bay, St Bride's Bay and western Carmarthen Bay. There are several small islands off the Pembrokeshire coast, the largest of which are Ramsey, Grassholm, Skokholm, Skomer and Caldey. The seas around Skomer and Skokholm, and some other areas off the Pembrokeshire coast are Marine protected areas.