Lake Chad sits on the border of the Sahel, a grassland which divides the Sahara Desert to the north and the more humid savannah to the south.

FORBES: Great Green Wall Plans to Stop Sahara

Opening an eye clinic staffed by Cuban doctors at Copacabana, a small town on Lake Titicaca just inside Bolivia's border with Peru, the two men proclaimed their fraternity.

ECONOMIST: Hugo Ch��vez's meddling backfires

Lake Powell, along the Arizona-Utah border, is at half its capacity.

NPR: Struggling over Water: A Series Overview

The Athabasca River flows north, into Lake Athabasca, which spans the Alberta-Saskatchewan border.

NEWYORKER: Unconventional Crude

Median house prices around Lake Tahoe, a ski area on the eastern border of California, have risen 60% in the past year.

ECONOMIST: The California housing market: Squeezed out | The

The French foreign ministry said on its website citizens were "officially advised not to go to the far north of Cameroon (the shores of Lake Chad in the South Maroua), and the border with Nigeria, until further notice".

BBC: French Cameroon hostages 'not released'

General Description Located in the north-west of the Republic of Congo and about 30 km east of the Gabon border, the Odzala Biosphere Reserve comprises an undulating plateau with the Blue Water Lake Moba and many natural saltpans.

UNESCO: Biosphere Reserve Information

The Lake Erie Correctional Institution in Conneaut, Ohio, just west of the Pennsylvania border, serves as an experiment in private prison administration by the Ohio Department of Corrections.

FORBES: Ohio Private Prison Reboots After Weekend Riot