but they, when they saw him walking on the sea, supposed that it was a ghost, and cried out;
But when they saw him walking upon the sea, they supposed it had been a spirit, and cried out:
But when they saw Him walking on the sea they thought it was a ghost, and raised a [deep, throaty] shriek of terror.
When they saw him walking on the lake, they thought he was a ghost and they screamed.
But when they saw him walking upon the sea, they thought it was an apparition, and they cried out.