In antiquity the island was known as Gerontia.
Gioura is known for its extraordinary "Cave of the Cyclops" on its southern side. The cave is the largest in the Sporades. Its opening faces the sea and leads into an area 40 x 50 metres with a height of 15 metres. The cave is "decorated" by many stalactites which have ceased developing.
The "Cave of the Cyclops" has been dug up with interesting finds not only from the classical and Roman periods but also from the Mesolithic and Neolithic periods indicative of hunting and fishing habits of that period.
Gioura is also home to a rare, protected species of wild goats - Apra hircus aegagrus.
Adamantios Sampson - "Excavation at the Cave of Cyclope, Youra". In E. Alram-Stern, ed., Die Agaische Frühzeit (2. serie). Forschungsbericht 1975-1993. Wien. pp. 507-520, 1996.