Iturralde Crater is a 5 mile (8 km) diameter circular feature in the Bolivia

Bolivia

Bolivia officially known as Plurinational State of Bolivia , is a landlocked country in central South America. It is the poorest country in South America...

n portion of the Amazon Rainforest

Amazon Rainforest

The Amazon Rainforest , also known in English as Amazonia or the Amazon Jungle, is a moist broadleaf forest that covers most of the Amazon Basin of South America...

, first identified from Landsat satellite imagery in 1985.
Being so circular, it is argued by some scientists that it may be a meteorite

Meteorite

A meteorite is a natural object originating in outer space that survives impact with the Earth's surface. Meteorites can be big or small. Most meteorites derive from small astronomical objects called meteoroids, but they are also sometimes produced by impacts of asteroids...

 impact crater

Impact crater

In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

. Because it is in an area of active sediment accumulation by rivers, it must be a geologically young feature, with estimates of its age ranging between 11,000 and 30,000 years.
Unlike other young craters, it is very flat, so if it is of impact origin, perhaps the crater sunk into the soft sediments leaving only a circular 'ghost' marking the original rim.
The site is very remote, but has been visited twice by scientific investigators, most recently by a team from NASA's Goddard Space Flight Center

Goddard Space Flight Center

The Goddard Space Flight Center is a major NASA space research laboratory established on May 1, 1959 as NASA's first space flight center. GSFC employs approximately 10,000 civil servants and contractors, and is located approximately northeast of Washington, D.C. in Greenbelt, Maryland, USA. GSFC,...

in September 2002.
In both cases, the expeditions failed to find conclusive evidence for the origin of the feature.

External links with images of Iturralde

• NASA Earth Observatory: Topographic Map of the Iturralde Structure, Bolivia
• NASA Earth Observatory: Iturralde Crater, Bolivia