| Büyük İlyosta Island | |
| Native Name: | Büyük İlyosta Adası |
| Native Name Lang: | Turkish |
| Map: | Turkey |
| Coordinates: | 39.3267°N 26.5372°W |
| Location: | Aegean Sea |
| Country: | Turkey |
| Country Admin Divisions Title: | İl (province) |
| Country Admin Divisions: | Balıkesir Province |
| Country Admin Divisions Title 1: | İlçe |
| Country Admin Divisions 1: | Ayvalık |
| Country 1 Area M2: | or |
| Country 1 Area Ha: | --> |
Büyük Ilyosta Island (literally "Great Ilyosta Island", also called Güneş Island ("Sun Island") is an Aegean island of Turkey. The name of the island is a changed form of the Greek name Eleos.[1]
The island at 39.3267°N 26.5372°W is a part of Ayvalık ilçe (district) of Balıkesir Province. Although the name of the island has the modifier "great", it is actually a medium size island of about . Its distance to main land (Anatolia) is about and to Greek island Lesbos is . The sea around the island is a popular diving spot.