Majuli or Majoli is a river island in the Brahmaputra River, Assam, India. The island had a total area of 1,250 square kilometres (483 sq mi), but having lost significantly to erosion it has an area of only 421.65 square kilometres (163 sq mi) in 2001. Majuli has shrunk as the river surrounding it has grown. Majuli is the largest river island in the world.

The island is formed by the Brahmaputra river in the south and the Kherkutia Xuti, an anabranch of the Brahmaputra, joined by the Subansiri River in the north. Majuli island is accessible by ferries from the City of Jorhat. The island is about 200 kilometres east from the state’s largest city -Guwahati. The island was formed due to course changes by the river Brahmaputra and its tributaries, mainly the Lohit. Majuli is also the abode of the Assamese neo-Vaisnavite culture.

Umananda Devaloi is a Shiva temple located at the Peacock Island in the middle of river Brahmaputra just opposite the office of the Deputy Commissioner of Kamrup or the Kachari Ghat in Guwahati. It was built by the Ahom King Gadadhar Singha (1681 – 1696), who was a devout Shaivaite.

It is known as smallest inhabited riverine island in the world. Country boats that are available on the bank of Brahmaputra take the visitors to the island.

source: https://en.wikipedia.org/wiki/Majuli
https://en.wikipedia.org/wiki/Umananda_Temple