Sandøya, Telemark

Sandøya is an island in Porsgrunn Municipality in Telemark county, Norway. The 1.5 km2 island lies just west of the smaller island of Løvøya and about 2 km to the east of the town of Brevik. The island lies at the mouth of the Eidangerfjorden, near where the Frierfjorden joins it to form the Langesundsfjorden. The island is only accessible by boat.

Most of the island's residents live on the southern part of the island, while the northern part of the island is heavily forested. The main urban area on the southwestern shore of the island is known as the village of Sandøya. The 0.31 km2 village has a population (2022) of 262 and a population density of 840 PD/km2. The remainder of the islands residents live right on the shore of the island.