The reference time for you Aquanaut travel time is the time at home where you normally live or work to set home time first actuate one of the pushers in the left-hand flank of the case as many times as needed to superpose the skeletonized and solid hour hand and to display the same color in the day / night indicator apertures at 3 o'clock (home) and at 9 o'clock (Local) Now you can unscrew the crown, genty pull it out, and more indicate the current time. The day /night indicator in the round aperture at 3 0'clock(home) lets you check whether you have set the correct time( white stands for thr daylight hours form 6 p.m., black for the nighttime form 6 p.m.to 6 a.m.) once the watch indicates the correct time, Push the crown home and screw it tight agin.