He began to study medicine at the University of Strasbourg before being transferred to the French Navy's medical school at Brest.

Upon returning to France, Crevaux gave an account of his journey to the Société de Géographie and was made a "Knight" of the Légion d'honneur.

He set out once again into the interior of French Guiana, this time he traveled up the Oyapock River to its source and again crossed the Tumuk Humak Mountains, near his modern namesake, Crevaux Peak.

He collected many biological specimens along the trip and returned to France where he was awarded the Gold Medal of the Société de Géographie.

After having explored 3,400 km of river in 161 days arrived in the Orinoco delta in gulf of Paria, collected a large harvest of objects of botany, zoology and anthropology, Dr. Crevaux is exhausted and must rest some time among the Gouaraounos Indians.

Crevaux was asked to undertake a fourth expedition, this time to explore the boundaries of the Amazon and Paraguay river basins.

He arrived in Argentina in December 1881 and was asked, by representatives of the Bolivian government, to explore the upper course of the Pilcomayo River.