 The highest point in the archipelago , Conachair ( ' the beacon ' ) at 430 metres ( 1 @,@ 410 ft ) , is on Hirta , immediately north of the village . In the southeast is Oiseval ( ' east fell ' ) , which reaches 290 metres ( 950 ft ) , and Mullach Mòr ( ' big hill summit ' ) 361 metres ( 1 @,@ 185 ft ) is due west of Conachair . Ruival ( ' red fell ' ) 137 metres ( 449 ft ) and Mullach Bi ( ' pillar summit ' ) 358 metres ( 1 @,@ 175 ft ) dominate the western cliffs . Boreray reaches 384 metres ( 1 @,@ 260 ft ) and Soay 378 metres ( 1 @,@ 240 ft ) . The extraordinary Stac an Armin reaches 196 metres ( 643 ft ) , and Stac Lee , 172 metres ( 564 ft ) , making them the highest sea stacks in Britain . 
