|Regional unit:||East Attica|
|Municipal unit:||Kalyvia Thorikou|
|Time zone:||EET/EEST (UTC+2/3)|
|Elevation (center):||5 m (16 ft)|
|Postal code:||190 10|
Lagonisi (Greek: Λαγονήσι meaning "rabbit island") is a beach settlement in the southern part of Kalyvia Thorikou in East Attica, Greece. It is situated on a peninsula by the Saronic Gulf. The Greek National Road 91 connects Lagonisi with Athens and Sounio. Lagonisi is located approximately 30 km southeast of Athens and 35 km northwest of Cape Sounio. Lagonisi is filled with luxury homes, beaches as well as several hotels and facilities lie within the Saronic and restaurants also cover the shoreline.