Penhale Sands forms part of the most extensive dune system in Cornwall; stretching for some 4 kilometres.

The coastal margin rises steeply to form a 50 metre high sand cliff, behind which the dunes rise to staggering 93 metres. The dunes are composed of nutrient poor calcareous shell sand, and provide an outstanding example of a sand dune system, with an exceptionally rich plant community including many rare and uncommon species.

The majority of the dunes are fixed grey dunes, but nearer the sea are areas of yellow dune with evidence of active blow-outs, many of which support ephemeral dune slack pools. The quality of this habitat and the rarity of dune slack pools nationally afforded Penhale Sands Flagship Pond status.

The list of rarities is long, but includes species such as Shore Dock Rumex rupestris, Flat-sedge Blysmus compressus, Variegated Horsetail Equisetum variegatum, Lesser Water-plantain Baldellia ranunculoides, Slender Spike-rush Eleocharis uniglumis, Scrambled-egg Lichen Fulgensia fulgens and Petalwort Petalophyllum ralfsii.

Penhale Dunes is not without its issues – artificial stabilisation of dune habitats, changes in hydrology and atmospheric nitrogen deposition is causing the wet dune slacks to scrub over and dry out. Funding through the Flagship Pond project has allowed vital conservation work to take place to restore lost habitat.