| Dioptra Island | |
| Map: | Antarctica#South Shetland Islands |
| Map Relief: | yes |
| Location: | Antarctica |
| Coordinates: | -63.2171°N -62.1925°W |
| Archipelago: | South Shetland Islands |
| Area Ha: | 0.92 |
| Length M: | 290 |
| Width M: | 45 |
| Population: | uninhabited |
| Country: | None |
| Treaty System: | Antarctic Treaty |
Dioptra Island (bg|остров Диоптра|ostrov Dioptra, pronounced as /bg/) is the conspicuous 290 m long in east-west direction and 45 m wide rocky island off the northwest extremity of Low Island in the South Shetland Islands, and separated from Beslen Island on the southeast by a passage narrowing to 21 m at points. Its surface area is 0.92 ha.
The feature is named after the classical surveying instrument dioptra, and in association with other names in the area deriving from the early development or use of geodetic instruments and methods.
Dioptra Island is located at -63.2206°N -62.1864°W,[1] which is 6.09 km northwest of Venev Point and 1.57 km northeast of Cape Wallace. British mapping in 2009.