Karaitivu (Tamil: காரைதீவு, romanized: Kāraitīvu; Sinhala: කරඩූව Karaḍūva) is an island off the coast of Jaffna peninsula in northern Sri Lanka, located approximately 15 kilometres (9 mi) north-west of the city of Jaffna. Karaitivu means "the island of karai shrubs" in Tamil and is derived from the Tamil words karai (Webera tetrandra, a thorny shrub from the family Rubiaceae) and tivu (island). Known as Amsterdam during Dutch colonial rule, the island has an area of 22.95 square kilometres (8.86 sq mi). The island is divided into nine village officer divisions whose combined population was 9,576 at the 2012 census.
Karaitivu is connected to Jaffna peninsula by a causeway and there is a ferry service from Kayts on the neighbouring island of Velanaitivu. Karainagar is the main settlement on the island. The popular Casuarina Beach is located on the island.