Ain is a department of geographic contrasts in Rhone-Alps : In the north the plain of Bresse is bordered by the river Saone and rises slightly towards the north-east. In the south-east the territory of the Dombes has more than a thousand ponds and lakes. In the east the mountain chain of the southern Jura overlooks the plain of Bresse. The busy transport axes to Italy and Switzerland crisscross the valleys. The Gex region is separated from the rest of the department by the last eastern mountain chain of the Jura where the highest elevation in the department, the Crêt de la Neige (1720 m), can be found. Gex belongs geographically to the Lake Geneva basin.

Ain is surrounded by the region of Burgundy with the department of Saône et Loire and by the region of Franche Comté with the department of Jura.

The river Saone represents the western border of the department. It is fed by three smaller rivers: the Reyssouze (76 km), the Veyle (68 km) and the Chalaronne (52 km). The river Rhône represents the departments border in the east and the south. Its main tributaries are the Seran (50 km) and notably the river Ain (190 km) which is fed itself by 118 small rivers and creeks.

Ain is situated at the crossroads of a large national and international flow of commodities and is therefore an important transit region. More than 4000 km of transport routes serve the department. In addition to a well developed transport network of former national roads, which were transferred to the department in 2007, the Department of Ain is crisscrossed by 220 km of highway.

For national and international flights the international airports of Lyon (Saint-Exupéry) and Geneva (Cointrin) are located within a rather short distance. The department of Ain disposes moreover of two waterways, the rivers Saone and Rhone, on which building material is shipped (gravel etc.). The most important harbour is situated in Jassans-Riottier at the river Saone.

Last but not least the railway network is of great importance, in particular the TGV-connections Paris-Geneva (with a stop in Bellegarde) and Paris-Lyon (passing by the Saone valley). A new TGV-connection through the Haut Bugey is under construction. It will reduce the actual travel time between Paris and Geneva by another 20 minutes. The regional TER (train and bus) network is important mainly as concerns the connection to Lyon.

The angling and cycling tourism (27 circuits with altogether more than 1,500 km) attracts numerous visitors each year. The tourist infrastructure is good and divers. The hotel and hospitality sector counts about 1,100 establishments (hotels, camping grounds, bed and breakfast (so-called "gîtes"), holiday apartments, guest rooms etc.). Their joined capacity amounts to 40,850 beds. During the season 2006 2.5 million nights have been passed in the department compared to 2.7 million in 2002 (source: Committee for Tourism in the Department of Ain, 2006). 15,000 hunters are registered in the departments, 3,000 to 4,000 of whom hunt in the Dombes, one of the best hunting regions for water birds in France.