Issued by Mexico in 1975, this airmail stamp commemorates the historic Acali Raft Expedition of 1973, an international scientific voyage across the Atlantic Ocean. The design depicts the experimental raft Acali, symbolizing human endurance and social research conducted at sea. Created to study cooperation and survival under confined maritime conditions, the expedition gained worldwide attention. The dramatic ocean scene and colorful sail make this issue visually striking within maritime and exploration themes. A desirable modern commemorative for collectors of ships, expeditions, and scientific history on stamps.