As the path drops towards Sandy Haven beach notice how the pebbles match the rocks in the surrounding cliffs. These include red mudstones, siltstones and sandstones. There are also green sandstones and pebbly conglomerates as well as a scattering of rock types which were transported to the area by ice sheets. These include igneous rocks from north Pembrokeshire as well as flints from the north-eastern tip of Ireland.

At this point you can see how the coastline within the Milford Haven Waterway has developed by the effects of wave action on the former valley slopes of the flooded river, exposing the distinctive rocks known as Old Red Sandstone.

Although marine erosion has created wave-cut platforms and sea cliffs within the waterway, in many places the original valley slopes have not been completely obliterated. Above the slope of the cliff, remnants of the valley can be seen, and the deposits that surround them have been revealed. These red or orange stony clays with aligned slabs of rock were formed by the down-slope movement of waterlogged soils above frozen ground in the latter part of the Ice Age.

Sandy Haven is a tidal estuary and an important habitat for a variety of estuarine birds including curlew, redshank, teal, widgeon, selduck, and mallard. On the water there are herring, great black-backed and lesser black-backed gulls. Although this appears to be an ideal habitat for choughs they are infrequent visitors and do not nest here.

On the far side of the Sandy Haven is estuarine woodland where herons and egrets often roost. Up stream from here it is possible to find Atlantic salt marsh habitat. This varies from looking like a green grassland sward to being covered with sea lavender and sea wormwood. The salt marshes are scattered throughout the tributaries and are atypical of salt marshes in that the areas as they are small and isolated, but have a high species and community diversity.