"Vamos a volver algún día."
Translation:We are going to come back someday.
I learned "vamos a la playa" means let's go to the beach. So I thought let's go return some day.
Remember, "ir a" + infinitive is the marker for a future event, equivalent to "going to do a thing" not going to a place.
Voy a comer (I'm going to eat)
Vamos a volver (We're going to return / come back)
Vamos a la playa (let's go to the beach)
Vamos a ir a la playa (we are going to go to the beach)
I keep making wrong assumptions about what they are trying to say. How would one say, "Let's come back some day"?
I'll see you someday (indefinite).
I'll see you some day next week (choice within a definite time).