The Amboni Caves are the most extensive limestone caves in East Africa. They are located 8 km north of Tanga City in Tanzania off the Tanga-Mombasa road. The caves were formed about 150 million years ago during the Jurassic age. It covers an area of 234 km². According to researchers the area was under water some 20 million years ago. There are altogether ten caves but only one is used for guided tours.