A humpback whale has been found dead in the Amazon jungle, sparking a search for answers from wildlife experts.

The carcass is estimated to be that of a year-old calf, which likely became separated from its mother.

It measured about eight metres long.

A dead whale has been found in the Amazon jungle. (Instagram/Bicho D'agua)

The body was found about 15 metres from the ocean on the Brazilian island of Marajo, at the mouth of the Amazon River.

Experts initially struggled to reach the body.

The whale was measured at eight metres long. (Instagram/Bicho D'agua)

The Bicho D'Agua Institute said in a post on Facebook that it was "totally understandable" that a carcass would be caught in the mangroves, suggesting the animal had died before being washed ashore.