Learn Finnish: Mitä enemmän matkailen, sitä enemmän haluan saunoa kotona. - The more I travel, the more I want to take a sauna at home.

It uses the structure mitä + comparative, followed by sitä + comparative. In this sentence, we have mitä enemmän (the more) and sitä enemmän (the more). You can think of it literally as "What more I travel, that more I want..."

Why are mitä and sitä used here instead of mikä and se?

Mitä and sitä are the partitive forms of mikä (what) and se (it/that). This specific comparative structure always requires these pronouns to be in the partitive case, which reflects an indefinite, uncountable degree of change.

What is the difference between matkailen and the more common verb matkustan?

While matkustaa is the standard verb for traveling from point A to point B, matkailla is a frequentative verb. It implies traveling as a hobby, touring, or traveling around continuously. It perfectly captures the ongoing lifestyle of traveling mentioned in this sentence.

Why use saunoa instead of a phrase like käydä saunassa (to visit the sauna)?

Saunoa is a dedicated verb meaning "to bathe in a sauna." While käydä saunassa or mennä saunaan are also perfectly correct, Finnish frequently turns common activities into single verbs. Using saunoa emphasizes the entire activity and ritual of taking a sauna rather than just the physical location.