CASTINE — Robert D. Ballard of Woods Hole, Mass., director of the Center for Marine Exploration at the Woods Hole Oceanographic Institution, will address the graduating class at Maine Maritime Academy’s 51st Commencement on April 30.

A veteran of nearly a hundred deep-sea expeditions, Ballard is best known for his discovery of the sunken British luxury liner Titanic. He also has discovered and filmed the sunken remains of the German battleship Bismarck and 11 ships from the lost fleet of Guadalcanal.

He served as a naval officer during the Vietnam War and was a consultant to the deputy chief of naval operations for submarine warfare. The author of eight books and more than 50 journal articles and scientific papers, he holds honorary doctorates from 11 colleges and universities in the United States and England.

Maine Maritime officials will present Ballard with an honorary doctor of science degree. The maritime academy also will honor Capt. Deborah Doane Dempsey of Lykes Bros. Steamship Co. in New Orleans. Dempsey, the first woman to graduate from Maine Maritime in 1976, is a licensed master in the U.S. Merchant Marine, qualified to command vessels of any tonnage, any ocean. In the mid-1980s, she became the first woman to serve as captain of a U.S.-flag ship in international commerce.

The commencement will be held 2 p.m. Saturday, April 30, at Alexander Fieldhouse.