20 Of this our Saviour the Prophet Jonas formed the type, when he prayed out of the belly of the whale, and said, I cried in my affliction, and so on; out of the belly of hell, and yet he was in the whale; but though in the whale, he says that he is in Hades; for he was a type of Christ, who was to descend into Hades. And after a few words, he says, in the person of Christ, prophesying most clearly, My head went down to the chasms of the mountains; and yet he was in the belly of the whale.
What mountains then encompass you? I know, he says, that I am a type of Him, who is to be laid in the Sepulchre hewn out of the rock. And though he was in the sea, Jonas says, I went down to the earth, since he was a type of Christ, who went down into the heart of the earth. And foreseeing the deeds of the Jews who persuaded the soldiers to lie, and told them, Say that they stole Him away, he says, By regarding lying vanities they forsook their own mercy. For He who had mercy on them came, and was crucified, and rose again, giving His own precious blood both for Jews and Gentiles; yet say they, Say that they stole Him away, having regard to lying vanities. But concerning His Resurrection, Esaias also says, He who brought up from the earth the great Shepherd of the sheep; he added the word, great, lest He should be thought on a level with the shepherds who had gone before Him.
Source: Catechetical Lectures (New Advent)