Porthtowan nestles in a north-west facing cove on the north coast between St Ives Bay to the west and Perranporth and Newquay to the east.

This steep valley is heavily impacted by historic mining activity and the valley slopes are coated in mobile mining scree. The eastern side is commercial with car parks and the western side is residential. The Porthtowan Stream runs through the centre of the area. On the left bank (western side) of the stream surface water enters the stream and the Unicorn Pub garden and adjacent playground are sandy. Below these the sand has been taken over by scrub and bramble.

The Surf Life Saving Club building and the SWW pumping station both sit on the beach close to the stream, on highly mobile ground.

The beach is fairly steep but wide. The sand is medium grained with even proportions of quartz, lithic and shell fragments. The upper beach is strewn with large cobbles and small boulders creating an armour layer.

There is a small area of sand dune on the western end, potentially encroaching on residential properties. At the eastern end an area of sand dune is fenced off, planted and protected with netting.

There are signs of cliff erosion at the western end, potentially affecting properties built upon the slope. At the eastern side, Glacial Head deposits (or possibly, in places, consolidated mine waste) provide a friable and highly erodible edge to the beach.