Bassas da India (French pronunciation: ​[basa da ɛ̃dja]; Malagasy: Nosy Bedimaky) is an uninhabited, roughly circular French atoll that is part of the French Southern and Antarctic Lands. Located in the southern Mozambique Channel, about halfway between Mozambique and Madagascar (about 385 km [239 mi] further east) and around 110 km (68 mi) northwest of Europa Island, the rim of the atoll averages around 100 metres (330 ft) in width and encloses a shallow lagoon of depth no greater than 15 m (49 ft). Overall, the atoll is about 10 km (6.2 mi) in diameter, rising steeply from the seabed 3,000 metres (9,800 ft) below to encircle an area (including lagoon) of 80 km² (31 sq mi). Its exclusive economic zone (EEZ), 123,700 km² (47,800 sq mi) in size, is contiguous with that of Europa Island.

The atoll consists of ten barren rocky islets, with no vegetation, totalling 20 hectares (49 acres) in area. Those on the north and east sides are 2.1 to 3.0 metres (7 to 10 ft) high, while those on the west and south sides are 1.2 metres (4 ft) high. The reef, whose coastline measures 35.2 km (21.9 mi), is completely covered by the sea from three hours before high tide to three hours afterward. The region is also subject to cyclones, making the atoll a long-time maritime hazard and the site of numerous shipwrecks.

Jaguar Seamount and Hall Tablemount lie, respectively, about 40 and 70 kilometres (25 and 43 mi) further southwest.