This is the 18387th most frequent Russian word.
экстремальное
Extreme.
The word "экстремальное" describes the character of skiing as challenging and involving risk.
Экстремальное катание на лыжах требует хорошей подготовки.
Extreme skiing requires good preparation.
The word "экстремального" is used to describe abstract concepts of danger or challenge sought by a person.
Его поиск экстремального привёл к удивительным приключениям.
His search for the extreme led to amazing adventures.
Here, "экстремальным" conveys the impressiveness or dramatic nature of the spectacle.