2. A Tsunami & An Earthquake Altered The Island
The North Sentinel Island is only the size of Manhattan city, in New York. In the year 2004, a tsunami is believed to have extended the boundaries of the island on the western and southern parts by around one kilometer. The earthquake that resulted lifted the plates underneath the island by around 2 meters.
This led to the exposure of corals that surrounded the island and today these corals have become shallow lagoons instead. However, there are also some corals that have on the other hand, become dry land.