Learn Spanish (Latin America): Vamos a viajar pasado mañana. - We are going to travel the day after tomorrow.

In Spanish, pasado can mean 'past' or 'after'. So pasado mañana literally translates to 'past tomorrow' or 'after tomorrow'. It is a standard set phrase, which is much more natural than trying to say el día después de mañana.

Why use vamos a viajar instead of the future tense viajaremos?

Both are correct, but in Latin American Spanish, using ir a + infinitive (like vamos a viajar) is the most common way to talk about future plans in everyday speech. The single-word future tense (viajaremos) often sounds a bit more formal or distant.

Since this lesson is about the future, why don't we use the subjunctive here?

We only use the present subjunctive for future events when they are introduced by a temporal word like cuando (when) or hasta que (until), indicating an event that hasn't happened yet. Because this sentence simply states a direct future plan without any of those trigger words, we just use the normal indicative vamos a viajar.