Haw. Rev. Stat. § 291C-86: Method of giving hand-and-arm signals.

All signals herein required given by hand and arm shall be given from the left side of the vehicle in the following manner and such signals shall indicate as follows:

(1) Left turn--hand and arm extended horizontally.

(2) Right turn--hand and arm extended upward, except bicyclists may signal using the right hand and arm extended horizontally from the right side of the bicycle.

(3) Stop or decrease speed--hand and arm extended downward.