The wooded shore road provides a view of this vast lake, nearly 48km long, the second largest in Ireland and dotted with countless islands. On one of them, in the lough's northwestern arm, stands the ruin of Hen's Castle, an O'Flaherty stronghold. It was defended by Grace O'Malley in 1570 when the Joyces, who had murdered her husband Donal O'Flaherty, tried to gain possession. Several years later, when it was besieged by English troops from Galway, Grace drove them back by pouring melted roof-lead on their heads and summoning help through an underground passage.