Hildasay has an area of , and is in elevation at its highest point. It consists of red-green
granite (epidotic
syenite) that was quarried for many years. The south coast has two narrow inlets, Cusa Voe and Tangi Voe. "West", the larger of two lochs, has a single islet. A satellite island,
Linga lies to the south east. A long line of
skerries and
holms lies to the north west. ==History==