Air travel is becoming cheaper.
      Her work involves a lot of travelling.

    You do not say 'a travel'.

     a long and difficult journey (NOT travel) through the mountains
I read during the train journey to work.
      Did you have a good journey? (=Were you comfortable, was the train on time etc?)

           my first trip to the States
       a business trip
      Was it a good trip?
(=Did you achieve what you wanted to or have a good time there?)

         a voyage across the ocean

       The crossing takes 90 minutes.

          Have a good flight!

    a mediterranean cruise
    a cruise around the world