Megalonisi (Greek: Μεγαλονήσι), also Nisiopi (Greek: Νησιώπη), is a long island near the west coast of the island Lesbos, North Aegean, Greece. It is situated in front of Sigri's harbour, and stretches across the mouth of the bay and acts as a buffer to the prevailing winds. In the middle stands Megalonisi Lighthouse to help ships navigate in the rough east Aegean Sea.
- Evelpidou, N.; Figueiredo, T.; Mauro, F.; Tecim, V.; Vassilopoulos, A. (2010). Natural Heritage from East to West: Case studies from 6 EU countries. Springer Berlin Heidelberg. p. 22. ISBN 978-3-642-01577-9. Retrieved 19 May 2019.
- Wire, E.; Reyes-Pergioudakis, D. (2010). The Lighthouses of Greece. Pineapple Press. p. 113. ISBN 978-1-56164-866-5. Retrieved 19 May 2019.
- Rowlett, Russ. "Lighthouses of Greece: Aegean Islands". The Lighthouse Directory. University of North Carolina at Chapel Hill.