At St Mary's Church Hall take the path on the right hand side, and then turn right into the country lane.

The waterway

The waterway at Milford Haven and at Sandy Haven Pill is a drowned river valley - known as a 'Ria'. The geological history of the waterway is complex.

A major fault - a fracture in the Earth's crust - runs along the central axis of the deep channel. This is known as the Ritec Fault, which can be traced from Tenby to Pembroke Dock, and at the mouth of the Milford Haven it is picked out again by the steep-sided, straight valley in which the village of Dale is situated. The fracture has been in existence for over 400 million years.

The development of the scenery of Milford Haven is much more recent in geological terms. Around 50 million years ago, rocks and sediments that had previously been beneath the sea were uplifted to form land. Remnants of these former marine erosion surfaces can be seen throughout Pembrokeshire including the plateau of the Dale Peninsula, visible from the coastal path just past Sandy Haven.

On the newly created land surface a river valley gradually developed following the Ritec fault. During the Ice Age - which lasted from 2 million to 10 thousand years ago - huge volumes of melt water from local ice sheets gouged out a deeper section within the valley floor. At that the time sea level was much lower than it is at present, as much of the earth's water was stored in extensive polar ice caps and continental glaciers.

Much of Britain was covered by ice, including an ice sheet that occupied the present area of the Irish Sea, which at its greatest extended to cover all of Pembrokeshire and the Bristol Channel area.

The most recent glaciation reached its peak around 18,000 years ago, and 10,000 years ago, the global climate improved, polar and continental ice cover diminished and the sea level began to rise rapidly. Over time the sea rose reaching a height similar to its present level 3,000 years ago. It was during this time that the landscape of Milford Haven that we see today was formed.

Milford Haven Waterway is up to 20 m deep in places and is reputedly the second deepest natural harbour in the world, second only to Sydney Harbour, Australia. It is its underlying geology that has contributed to the development of Milford Haven as a port; currently the largest in Wales and the fifth largest in the UK.