Elounda is set on a bay facing the Sinalonga Peninsula, which is connected to the mainland by a narrow causeway. The small island of Spinalonga sits in the entrance of the bay and has a Venetian fortress. Spinaloga is a small rocky islet, in the entrance of the lagoon. The name Spinaloga is Venetian (Spina=thorn, longa=long). Spinaloga, since antiquity, has protected the harbour of ancient Olous. It used to be one of the most powerful fortresses of the Venetian Crete, and it was never conquered.

Its high walls were built in 1579 and are preserved today intact. In 1630 it had 35 cannons. For half a century after the Turkish conquest of Crete, Spinaloga remained in the hands of the Venetians and was a refuge for many Christians who fled there to escape from the Turks. In 1715 the islet was handed over to the Turks with the conclusion of a treaty. From 1912 to 1958 the islet served as a sanatorium for the lepers of Crete. Today the entrance is free for the visitors who are attracted by its history and architecture.