Rashi: It is a Gibor in Yir'as Hashem, i.e. Chizkiyah. Radak - he was shelter for his generation.

Malbim: Chizkiyah, even though he is a physical man composed of the four 'elements' (earth, fire, wind and water), he rules over them and protects from them.

Rashi: Like a shelter of rock. People hide in it from wind and great heat. So the remnant of the 10 tribes will trust in Chizkiyah.

Radak: It is a place where one hides from wind or a flow of rain (Malbim - the elements of wind and water). So Chizkiyah's generation will hide in his virtue to be saved from the evil of Melech Ashur.

Rashi: It is an expression of dryness.

Radak: This is like streams that one finds in an arid place.

Malbim: The water protects against dryness and heat due to the element of fire.

Rashi: In a place of sun, the land is weary and dry, and desires shade.

Radak: It is like shade of a great rock in a dry desert without shade. Those who go in it are thirsty and hot. If they find water or shade of a rock, it revives them. So Chizkiyah - Yisrael were in pain and captivity in the days of his father. Kaved is great, like "Amecha ha'Kaved ha'Zeh" (Melachim I, 3:9).

Malbim: Where the element of earth is bad and damages, and the land is dry and the rock is heavy, this is a protection from the evil of that element.