As a Retired US Army MSG, I wear my Mess Dress Uniforms on cruises on formal nights. I have both the "Blue" and "White" US Army mess dress uniforms. I decide which one to take and wear, based on the weather and time of year.
On my first cruises, I rented a tux and wore my decorations, etc on it. I also observed others on these trips wearing there mess dress, as service retirees.
I decided that I would start doing so as well. The rented Tux was costing me around $100. per cruise. I already had the mess dress uniforms. Even if I had to buy a Mess dress uniform, it would pay for it self in a short while at that rate. (We cruise at least twice a year.)
I am proud of my service (30+ Years in both the Regular Army, Air Force Reserve and Army reserve. As you can no doubt tell from my avatar and screen name, I served in the US Army's Special Forces (SOCOM) for over 10 years of this time.
I do not fear terrorist activities on board ship, nor am I shy about wearing the military uniform on board the ship on formal nights.
I do not wear my uniform off the ship nor in some places (Outside the US.) or call any attention to myself as an Ameican, or former member of the American Armed forces.
In reviewing the AR's on the wear of uniforms for retirees, I found that there was enough room in them to allow for wear of the Mess dress on such activities such as the formal night, especially since the crew does wear military uniforms to the formal.
In 06 May, I'll be boarding the Coral Princess for a trip through the Panama Canal. I'll be wearing my White mess dress on those three formal nights.
BTW: Those that do wear their Mess Dress, especially those that served in SOCOM units, should put their "Challenge" coin in their pocket or be ready to buy the drinks!!