Antoine Jean de Laval (1664 – 1728) was a French Jesuit priest and scientist active in the late 16th and early 17th century. Laval was a royal professor of hydrography and mathematics based in the city of Toulon. Laval is best known for his 1720 voyage along the Gulf Coast to triangulate the exact longitude of the Mouth of the Mississippi River. Laval never obtained his objective, in fact may never have seen the Mississippi River, but did publish an important account of the region in his 1728, Voyage de la Louisiane.