Leros (Greek: Λέρος) is a Greek island and municipality in the Dodecanese in the southern Aegean Sea. It lies 317 kilometres (197 miles) (171 nautical miles) from Athens's port of Piraeus, from which it can be reached by an 11-hour ferry ride (or by a 45-minute flight from Athens). Leros is part of the Kalymnos regional unit.