This is Inter-Island Airways S-38 no. 2 "Maui" taxiing to the beach end of the dirt runway at Maalaea which was oriented parallel to the prevailing trade winds. It will make a 180 deg. turn and take off into the trades. Kahului harbor was the backup "field" which was used on at least two occasions when the Maalea strip was too muddy. The fact that the S-38 was an amphibian helped the public to accept air travel as safe. The airline took delivery of their fourth and final S-38 in mid-1931.
Detail of the Pratt & Whitney "Wasp" engine used in the aircraft. It is pictured in Hangar 1 at John Rodgers Airport in Honolulu, 1934. Enlarge