What is "makronisos"

Makronisos (, lit. Long Island), or Makronisi, is an island in the Aegean sea, in Greece. It is located close to the coast of Attica, facing the port of Lavrio. The island has an elongated shape, north to south, around east to west, and its terrain is arid and rocky.

In ancient times the island was called Helena.

It is part of the Kea-Kythnos regional unit and in the municipality of Kea.

Today it is uninhabited but it was used as a prison island from the time of the Greek Civil War until the restoration of democracy, following the collapse of the Regime of the Colonels in 1974. Because of its history, it is considered as a monument of the civil war era; therefore the island and the original structures on it are protected from alteration.

The Kea Channel between Makronisos and neighbouring Kea was the site of the sinking, in 1916, of HMHS Britannic, sister ship of the RMS Titanic.