Originally from here.

39. He therefore brought him to Epidaurus, a town in Dalmatia, where he stayed for a few days in the country near, but could not be hid. An enormous serpent, of the sort which the people of those parts call boas because they are so large that they often swallow oxen, was ravaging the whole province far and wide, and was devouring not only flocks and herds, but husbandmen and shepherds who were drawn in by the force of its breathing. He ordered a pyre to be prepared for it, then sent up a prayer to Christ, called forth the reptile, bade it climb the pile of wood, and then applied the fire. And so before all the people he burnt the savage beast to ashes. But now he began anxiously to ask what he was to do, whither to betake himself. Once more he prepared for flight, and in thought ranged through solitary lands, grieving that his miracles could speak of him though his tongue was silent.

40. At that time there was an earthquake over the whole world, following on the death of Julian, which caused the sea to burst its bounds, and left ships hanging on the edge of mountain steeps. It seemed as though God were threatening a second deluge, or all things were returning to original chaos. When the people of Epidaurus saw this, I mean the roaring waves and heaving waters and the swirling billows mountain-high dashing on the shore, fearing that what they saw had happened elsewhere might befall them and their town be utterly destroyed, they made their way to the old man, and as if preparing for a battle placed him on the shore. After making the sign of the cross three times on the sand, he faced the sea, stretched out his hands, and no one would believe to what a height the swelling sea stood like a wall before him. It roared for a long time as if indignant at the barrier, then little by little sank to its level. Epidaurus and all the region roundabout tell the story to this day, and mothers teach their children to hand down the remembrance of it to posterity. Verily, what was said to the Apostles, If you have faith, you shall say to this mountain, Remove into the sea, and it shall be done, may be even literally fulfilled, provided one has such faith as the Lord commanded the Apostles to have. For what difference does it make whether a mountain descends into the sea, or huge mountains of waters everywhere else fluid suddenly become hard as rock at the old man’s feet?