Learn Finnish: Tämän aavikon pinta-ala on maailman toiseksi suurin. - This desert's surface area is the world's second largest.

In Finnish, when you rank something with a superlative (like 'second largest' or 'third fastest'), the ordinal number takes the translative case (-ksi). It acts as a fixed adverb modifying the superlative adjective. The superlative itself (suurin) takes whatever case is required by its role in the sentence.

Does the translative ordinal (toiseksi) change if the main subject is in a different case?

No, in this ranking construction, the ordinal number stays locked in the translative case regardless of the noun's case. For example, 'in the second largest desert' would be toiseksi suurimmassa aavikossa. The superlative and the noun change to the inessive case, but toiseksi remains completely unchanged.

Why do we use the genitive maailman instead of the inessive maailmassa (in the world)?

While you will occasionally hear the inessive used, Finnish strongly prefers using the genitive case immediately before a superlative to express 'the most [adjective] in the world'. You can translate it literally as 'the world's second largest'.

What is the literal breakdown of the compound word pinta-ala?

It combines pinta (surface) and ala (area or field). It is the standard Finnish term for surface area. As a quick refresher for compound words: if you need to put this word into a different case later, remember that usually only the second half changes, such as pinta-alaa in the partitive.