On 28 June, small earthquakes rocked the western end of the island, and these continued occurring day after day. The crew of a passing ship had other ideas: the captain noted that the water under the smoke was bubbling vigorously. He was convinced that what they were dealing with was a sea monster. This disturbance was, in fact, a volcano erupting from just under the surface of the Mediterranean Sea. By the 17th of July, a new island some 25 feet high had appeared off the coast of Sicily.