This 80 centavos airmail stamp from Mexico, issued in 1975, commemorates the "Acali" raft expedition of 1973. The stamp features a vivid image of the raft on the open sea, with its brightly painted sail and crew on deck. The expedition, launched on August 21, 1973, aimed to study human behavior in isolation. Designed by H. Rodríguez and inscribed with “T.I.E.V.”, it captures a unique scientific and sociological journey across the Atlantic. A striking piece for collectors interested in exploration-themed issues.