At the start of the game, when you get out of the cage at Phobos, the airport will be under renovation and you can only go to Beachwell. Next time you come here, the renovation will have been completed and all normal routes and facilities will be available.

Marinara Trench and Elf Planet are easy to identify from the word lengths.
Beachwell and Patsville are both long names with two l's near the end, but Patsville has another letter after the two l's whereas Beachwell doesn't.
Phobos and Uranus are both six-letter words ending in s, but the 3rd and 5th letters in Phobos are the same, whereas for Uranus it's the 1st and 5th letter.