Ovalau (pronounced [oβaˈlau]) is the sixth largest island in Fiji. It is located in Lomaiviti Archipelago. Situated at 17.70° South and 178.8° East, (60 km north east from the national capital Suva and 20 km off the east coast of Viti Levu), the island is about 13 kilometers long and 10 kilometers wide. It covers a total area of 106.4 square kilometers and has a population of around 8,900 according to the census of 2017. Levuka, Fiji's former capital, is the largest place on the island, and is the only urban area in Lomaiviti.

Ovalau is characterized by its rugged topography, with little flat land apart from the Lovoni Valley in the centre of the island. The island is an eroded volcanic crater with a narrow belt of flat to undulating country between the encircling lagoon and the steep crater sides. The highest peaks are Nadelaiovalau, with an elevation of 625 meters, in the east, and Tomuna, 526 meters, in the south. Moturiki is just off the southwest coast of Ovalau. To the north-west is Naigani, and to the east is Wakaya.

Ovalau has four administrative areas (tikina), which are divided into 23 traditional communities (koros) and the city of Levuka.

Levuka includes the koros of Vagadaci (315), Waitovu (449, incl. Wailailai settlement), Vuma (211), Toki (194), Vatukalo (270), Nawowo (98), Yaravudi (161), Taviya (198), and Rukuruku (334).

Nasinu includes the koros of Nasinu (137), Naikorokoro (188, incl. Nasovo settlement), Tokou (442), Natokalau (398), and Draiba (202).

Lovoni includes the villages of Lovoni (196), Nacobo (279), Nukutocia (229), Visoto (252), and Vuniisavu (143).

Bureta includes the koros of Naiviteitei (75), Nasaga (151), and Navuloa (205, incl. Tivi settlement).

There are also the villages of Wainaloka (330), Viro (260), and Nasaumatua (117), as well as smaller settlements.