Cuando volvamos, me gustaría hacer otra ruta hasta la cima y llevar una cantimplora más grande.

Because after cuando referring to a future event, Spanish normally uses the present subjunctive, not the future tense.

• Cuando volvamos = when we come back
• Not cuando volveremos

This is a very common pattern:

• Cuando llegue, te llamo. = When I arrive, I’ll call you.
• Cuando tengamos tiempo, lo hacemos. = When we have time, we’ll do it.

If cuando refers to something habitual or past, then you use other tenses:

• Cuando volvemos, siempre estamos cansados. = When we come back, we’re always tired.
• Cuando volvimos, estaba lloviendo. = When we came back, it was raining.

So here, cuando volvamos is correct because the return hasn’t happened yet.

Volvamos is the 1st person plural present subjunctive of volver.

• Infinitive: volver = to return / to come back
• Present subjunctive:
  • yo vuelva
  • tú vuelvas
  • él/ella vuelva
  • nosotros volvamos
  • vosotros volváis
  • ellos vuelvan

Notice the stem change o > ue happens in most forms, but not in nosotros and vosotros:

• vuelva, vuelvas...
• but volvamos, volváis

Me gustaría means I would like, which sounds softer and more tentative than quiero (I want).

• Quiero hacer otra ruta = I want to do another route
• Me gustaría hacer otra ruta = I’d like to do another route

Spanish often uses gustaría to sound polite, reflective, or less direct. In this sentence, it gives the idea of a wish or preference for the future.

Also, gustaría comes from gustar, but in this structure it works like:

• Me gustaría + infinitive
• I would like + to do something

Examples:

• Me gustaría descansar. = I’d like to rest.
• Nos gustaría volver. = We’d like to come back.

Because gustar works differently from English to like.

In Spanish, gustar is more like to be pleasing to. So:

• Me gusta = It pleases me = I like it
• Me gustaría = It would please me = I would like

The me shows to me.

Other forms:

• te gustaría = you would like
• le gustaría = he/she/you (formal) would like
• nos gustaría = we would like

So me gustaría hacer otra ruta literally works like Doing another route would please me, but in natural English it means I’d like to do another route.

Yes. In Spanish, hacer una ruta is a normal way to say to do / take / go on a route, especially for hiking, walking, or driving.

Here ruta means a route, trail, or itinerary, depending on context.

So:

• hacer una ruta = to do a route / go on a trail / take a route

In hiking contexts, English might naturally say:

• do another hike
• take another trail
• go on another route

Spanish prefers hacer in many expressions where English uses a different verb.

Otra ruta means another route or a different trail/hike.

• otra = another / other
• ruta = route / trail / hike

Because ruta is feminine singular, the adjective/determiner must match:

• otro camino = another path
• otra ruta = another route

In context, it probably suggests doing a different hiking route next time.

Both can be possible in Spanish, but they suggest slightly different things.

• hasta la cima = all the way up to the summit
• a la cima = to the summit

Hasta emphasizes the endpoint more strongly, often with the sense of reaching it after a journey. In a hiking sentence, hasta la cima sounds very natural because it highlights going up as far as the top.

So:

• hacer otra ruta hasta la cima = do another route up to the summit

Because in Spanish, nouns often need an article where English might not use one.

• la cima = the summit / the top

After prepositions like hasta, Spanish still normally keeps the article if the noun naturally takes one:

• hasta la playa
• hasta el pueblo
• hasta la cima

Saying hasta cima would sound incomplete or ungrammatical in standard Spanish.

Because llevar means to take / carry something from your current point toward another place, while traer means to bring something toward the speaker or destination point.

In this hiking context:

• llevar una cantimplora = take/carry a water bottle/canteen
• traer una cantimplora would suggest bring a canteen toward where someone is

Since the speaker is talking about what they want to have with them on the route, llevar is the natural choice.

A cantimplora is a canteen or water flask/bottle, especially one used for hiking, camping, or outdoor activities.

In Spain, cantimplora sounds quite natural for an outdoor container for water. Depending on context, English might translate it as:

• canteen
• water bottle
• flask

Here una cantimplora más grande means a bigger canteen/water bottle.

In Spanish, descriptive adjectives usually come after the noun.

• una cantimplora más grande = a bigger canteen
• literally: a canteen bigger

This is the normal word order:

• una casa grande = a big house
• un camino largo = a long path

With comparisons like más grande, the adjective phrase also normally goes after the noun:

• una mochila más pequeña = a smaller backpack
• una ruta más difícil = a more difficult route

Because Spanish usually forms the comparative with:

• más + adjective = more + adjective

So:

• grande = big
• más grande = bigger

This is much more common than having a special separate comparative word, unlike English big → bigger.

Examples:

• más alto = taller
• más corto = shorter
• más difícil = more difficult

So una cantimplora más grande literally means a more big canteen, but naturally it means a bigger canteen.

Because me gustaría can be followed by one or more infinitives to express the things the speaker would like to do.

Here the structure is:

• me gustaría
  • hacer otra ruta hasta la cima
  • y llevar una cantimplora más grande

So the speaker would like:

1. to do another route up to the summit
2. to carry/take a bigger canteen

This is very common in Spanish:

• Me gustaría viajar y descansar. = I’d like to travel and rest.
• Nos gustaría comer fuera y volver temprano. = We’d like to eat out and come back early.

By itself, volvamos can sometimes be a nosotros command meaning let’s return. But here it does not mean that, because the context makes it clearly a subjunctive form after cuando.

• Cuando volvamos... = When we come back...

Compare:

• Volvamos a casa. = Let’s go back home.
• Cuando volvamos a casa... = When we go back home...

So the surrounding words tell you which meaning it has.