He traveled overland through Armenia to either the Empire of Trebizond or through the Sultanate of Rum to the Simisso on the Black Sea, then by boat to Constantinople, where he had an audience with Andronicus II Palaeologus. Bar Sauma's writings give a particularly enthusiastic description of the beautiful Hagia Sophia. He next traveled to Italy, again journeying by ship. As their course took them past the island of Sicily, he witnessed and recorded the great eruption of Mount Etna on 18 June 1287. A few days after his arrival, he also witnessed a naval battle in the Bay of Sorrento on St. John's Day, 24 June 1287, during the conflict of the Sicilian Vespers. The battle was between the fleet of Charles II (whom he calls Irid Shardalo, i.e. Il re Charles Due), who had welcomed him in his realm, and James II of Aragon, king of Sicily (whom he calls Irid Arkon, i.e. Il re de Aragon). According to Bar Sauma, James II was victorious, and his forces killed 12,000 men.