Haze gray and underway is a United States Navy saying that refers to surface ships in what seems like continuous duty at sea, in contrast to submarines or naval units in ceremonial roles or in port. Surface ship sailors also use this to distinguish themselves from submarine sailors.

The United States Navy saying "haze gray and underway" refers firstly to the color "haze gray". Haze gray is a paint color scheme used by USN warships to make the ships harder to see clearly. The gray color reduces the contrast of the ships with the horizon, and reduces the vertical patterns in the ship's appearance. It is the color of USN combatant ships, as opposed to the dark gray or black color submarines, the bright colors of ceremonial vessels and aircraft, or the white of hospital ships. Secondly, "underway", taken from the old sailing term "under weigh", as opposed to being anchored, docked, alongside, moored or otherwise attached to a fixed place.

Thus, "haze gray and underway" is shorthand for naval surface warships at sea. It is also used to refer to life in a vessel at sea with the working Navy, as opposed to shore postings.

Surface ships are meant to be underway, that’s why they are only tied to the pier. After my ship was done with its overhaul we were underway far more days than we were in port.
A typical month for us was as follows:

April 1-3: INPORT Norfolk Va

April 4: DEPART Norfolk Va

April 4-10: Underway

April11: INPORT Gitmo

April 12-20 Underway

April 21: INPORT Mayport Fl.

April 22-29: Underway

April 30: INPORT Norfolk Va.

We had times when we would be out for over 30 days without seeing land. Then we would see land but still stay out for a few more weeks. There are times when ships will stay out to sea ever longer. If you join the Navy you will be Haze Grey and Underawy, but that is what the Navy does.