Born in Morges on Lake Geneva, he worked as a professor of medicine at the University of Lausanne.
But his real love was the lake; his investigations of biology, chemistry, water circulation, and sedimentation, and most importantly their interactions, established the foundation of a new discipline. In his chief work, Le Léman, published in three volumes between 1892 and 1904, he named his activity limnology in analogy with oceanography ("limnography" could have been confused with the limnograph, which measures water level in lakes).
He discovered the phenomenon of density currents in lakes, and explained seiches, the rhythmic oscillations observed in enclosed waters.
The Institute F.-A. Forel of the University of Geneva is named after Forel.