“Los yoghurts más frescos de Chile.”

The superlative is used to make a comparison between multiple items and it is used to stress a relationship of superiority between one item and the rest. In English, to form a superlative we usually add “-est” to an adjective. In Spanish, however, we’re going to start with an article and add “más” / “menos” before adjective to create the superlative.

el/la/los/las + (noun) + más/menos + (adjective) + de…

Some adjectives have irregular comparative forms which you saw when discussing comparisons of inequality. When applied to the superlative constructions they retain their irregular forms:

definite article + irregular comparative form + de…

bueno → el mejor (the best)
malo → el peor (the worst)
grande → el mayor (the oldest – people)
pequeño → el menor (the youngest – people)

• Cuando los colegas coreanos salen a comer, el mayor paga. (When Korean colleagues go out to eat, the oldest pays.)
• Muchos europeos son trilingües, pero en general los africanos son los más multilingües del mundo. (Many Europeans are trilingual, but in general Africans are the most multilingual in the world.)