There are plenty of reasons to don your reef shoes and go exploring at low tide in Ha'apai. One of the most intriguing, however, is the ancient petroglyphs carved into Houmale'eia Beach (Matafonua Beach). Head to the eastern side of Foa Island's sandy point and you will some ancient Polynesian carvings in the beach's flat rock. The carvings depict an array of images including human feet, triangular-bodied people, lizards, dogs and turtles.