The captain's private dining room aboard Enterprise NX-01, where Jonathan Archer regularly ate with T'Pol and Tucker and entertained visiting dignitaries.
The captain's mess is a small dining room next to the galley on Enterprise NX-01. Unlike the crew's mess hall it seats only a few, and it is served by a steward with meals prepared by the ship's unseen chef.
Archer makes a habit of eating there with his two most senior officers, T'Pol and Tucker. Their dinners are one of the series' regular settings for arguments about Vulcan caution and human impulsiveness and for news delivered away from the bridge. T'Pol's practice of eating even breadsticks with a knife and fork is established there in Broken Bow.
The room is also used for diplomacy, with guests including the Vulcan Captain Vanik in Breaking the Ice; the Kreetassans, by contrast, are famously offended by the sight of the crew eating in company.