Thai King Maha and Queen Suthida took the Tube as part of the opening of a new station in Bangkok on Saturday.
The royal couple sat on padded cushions in what looked to be a normal subway car for the opening of the new extension of the Metropolitan Rapid Transit (MRT) Blue Line.
Army officers in white uniforms sat on the car floor in front of them so as to be below the level of the king.
Meanwhile, pro-democracy protesters rallied again in the centre of the city at the Democracy Monument under the name “Mob Fest” and called for government and monarchy reforms.
Thousands of royalists dressed in yellow also gathered and marched to show their support for the king.
In the afternoon, angry high school students calling themselves the Bad Student Movement rallied outside the Thai education ministry, calling on the education minister to resign. They staged a fake funeral for him.
“He has failed to reform the education system so he is dead to us,” Anna, 15, said as she put flowers into the fake coffin.
The students are calling for an overhaul of the school system, curriculum, strict rules, dress codes and standardised haircuts.