What great surprise awaits Gulliver when he awakens on the rocky island?

Do you mean the rocky island of Lilliput? When Gulliver awakens, he is lying on his back. He finds himself unable to sit up or move at all. His "Arms and Legs were strongly fastened on each side to the Ground; and [his] Hair, which was long and thick, tied down in the same manner." He feels something moving along his body almost up to his chin, at which point he sees that it is "a human Creature not six Inches high, with a Bow and Arrow in his Hands, and a Quiver at his Back." Gulliver will later learn that these creatures are called Lilliputians.