Ischia is not a single volcano but a crowded field of some forty eruptive vents, the youngest of which last spoke in 1302. That eruption sent the Arso lava flow to the sea near Ischia Ponte, where its black crust is still visible from the water. The island covers roughly 46 square kilometres, and its perimeter — about 34 kilometres of cliff, cove and terraced vineyard — is the natural course of an ischia boat tour around island. Greeks from Euboea settled here around 770 BC at Pithekoussai, making it one of the earliest Hellenic colonies in the western Mediterranean. Amphora fragments recovered above Lacco Ameno carry some of the oldest Greek writing found in Italy. Later the Romans came for the springs; the same geothermal system that heats Cavascura and Sorgeto still vents beneath the seabed, warming pockets of water that swimmers notice without warning. What makes the coastline worth circling is that no two sectors resemble each other. The northern flank around Casamicciola and Lacco Ameno is low and domed, punctuated by Il Fungo, a mushroom-shaped block of volcanic tuff sculpted by wave erosion. Westward at Forio, the Torre del Soccorso church sits white against the cliff, and the Baia di Citara opens toward sunsets that painters have chased since the nineteenth century. The southern shore is the wildest: Sant'Angelo's tied island, the sheer walls below Serrara Fontana, and the Grotta del Mago cut into the rock near Barano. On the eastern side the Castello Aragonese rises on its own islet, joined to Ischia Ponte by a 220-metre causeway built under Alfonso of Aragon in 1441. Guided ischia island coastal cruise routes exist because this variety cannot be read from land. Roads climb inland, away from the shore, and the best-known sea caves have no path down. Sailing traditions here are old and practical — the gozzo, a broad wooden fishing hull, remains the template for many boats still working out of Riva Destra and Riva Sinistra. Contemporary ischia boat tour around island tours follow the same clockwise or anticlockwise arcs that fishermen used to read wind and current. The 789-metre summit of Monte Epomeo stays in view for most of the circuit, a reminder that the whole island is one uplifted block of green tuff pushed out of the sea.