Pembrokeshire has some of the oldest rock formations in the world (over 3000 million years old). Most of the county's coastline consists of rugged cliffs and coves broken up by some of the best sandy beaches in Wales. The Pembrokeshire Coast National Park covers around 230 square miles with roughly 180 of coastline. All of the park lies within 10 miles of the coast.Boat trips are available to many of the island nature reserves off the Pembrokeshire coast such as Ramsey Island off St Davids and Caldey Island from Tenby. The largest theme park in the area is Oakwood at Canaston Bridge which has Europes largest wooden roller coaster with drops of over 80 feet.