The bay is delineated to the south by a headland known as the Giant’s Castle, which is an Iron Age cliff fort, and Porth Hellick Down and Porth Hellick Point to the north.Ordnance Survey: Landranger map sheet 203 Land's End At low tide a wide expanse of sand and rocks are exposed and a bar of fine shingle provides a barrier from the sea to form the largest area of (usually) fresh water on St Mary’s. A stream rises in Holy Vale and flows south through Higher Moors to the sea at Porth Hellick. In its half-mile length it falls less than 25 feet and has barely cut a river bed through the marsh; but feeds the pool with fresh water.
