Is it Mount Desert Island or Mount Dessert Island?

Samuel Champlain, a French navigator and cartographer, sailed by Mount Desert Island in 1604. He named it "Isles des Monts Desert," with the accent on the last syllable, as it is in the French language. He wasn't implying that it was a desert. The phrase means "island of barren mountains." That's why it's pronounced both as it is spelled and as the French meaning would be pronounced (dessert).