Imperative: Ir Nosotros command
In the example used " Vamos a nadar" which translate to Let's go swim, is incorrect to write the sentence as "Vamos nadando" for let's go swiming
Vamos a nadar can also be We are going to swim with no let's involved.
The imperative (exhortation) for the 1st person, plural for saying "let's go"... can also me made using the subjunctive mood of the the verb. (nademos).
I'd like to hear a native's explanation of the Vamos nadando as I saw that ir+gerund was one of the periphrases mentioned our new Reference topic on paraphrasis.
Oops, maybe I should change that tense to had seen as I don't see the article anymore, just the comments.
" Vamos a nadar"also translates to "Let's go swimming."
After "Vamos a" you will use the infinitive verb form.
For another example: "Let's go eat" is "Vamos a comer."
I've always seen it "Vamos a nadar".