Pius "Mau" Piailug (pronounced ; 1932 – July 12, 2010) was a Micronesian navigator from the Carolinian island of Satawal, best known as a teacher of traditional, non-instrument wayfinding methods for deep-sea voyaging. Mau's Carolinian navigation system—which relies on navigational clues using the sun and stars, winds and clouds, seas and swells, and birds and fish—was acquired through rote learning passed down through teachings in the oral tradition.
He earned the title of master navigator (palu) by the age of eighteen, around the time the first American missionaries arrived in Satawal. As he neared middle age, Mau grew concerned that the practice of navigation in Satawal would disappear as his people became acculturated to Western values. To preserve the navigational tradition for future generations, Mau shared his knowledge with the Polynesian Voyaging Society (PVS). With Mau's help, PVS created the Hōkūle‘a, a modern reconstruction of a double-hulled Hawaiian voyaging canoe to test lost navigational techniques. The successful, non-instrument sailing of Hōkūle‘a to Tahiti in 1976, proved the efficacy of Mau's navigational system to the world.
Later in life, Mau was respectfully known as a grandmaster navigator, and he was called "Papa Mau" by his friends with great reverence and affection. He received an honorary degree from the University of Hawaii, and he was honored by the Smithsonian Institution and the Bishop Museum for his contributions to maritime history.