# The Heat of the Earth: Fumaroles and Thermal Waters **At a glance:** Casamicciola's thermal waters and fumaroles are the visible sign of the heat of Ischia's volcanic system, now dormant. The Monte Cito fumaroles approach 100 °C, while the springs of the town's four hydrothermal basins, Gurgitello, Cotto and Sinigallia, La Rita and Castiglione, emerge at between 50 and 72 °C. ## Useful information - **Type:** Volcanic and geological history - **Coordinates:** 40.747400, 13.907500 - **Hottest fumaroles:** Close to 100 °C (Monte Cito, Monte Nuovo, Maronti) - **Hydrothermal basins:** Gurgitello, Cotto and Sinigallia, La Rita, Castiglione - **Spring temperatures:** Between about 50 and 72 °C - **Recommended route:** Alum Trail (Sentiero dell'Allume), about 8.4 km, 3 hours ## A volcano that heats the water Italy's Civil Protection Department describes Ischia as a still-active volcanic area, as shown by intense hydrothermal activity in the form of hot water and gas emissions. Heat from the deep magmatic system warms the water circulating through the island's rocks; where fractures and faults provide a way out, the water rises to the surface as a thermal spring and the steam as a fumarole. To understand how this landscape formed, read [The volcanic origins of Casamicciola](https://visitcasamicciola.com/en/history/volcanic-origins-of-casamicciola/). ## The fumaroles Fumaroles are jets of steam, often mixed with other gases, that escape from cracks in the ground. According to the Civil Protection Department, on Ischia they reach temperatures close to 100 °C on the slopes of Monte Nuovo and Monte Cito and along the Maronti shore, while elsewhere they do not exceed 46 °C. ### Monte Cito and the alum route The fumarole field of [Monte Cito](https://visitcasamicciola.com/en/nature/monte-cito-solfatara-fumaroles/), at around 220 metres above sea level, is recognisable by the ground, which takes on colours ranging from white to purple to deep yellow. It is crossed by the [Sentiero dell'Allume](https://visitcasamicciola.com/en/nature/alum-trail/) (Alum Trail), which follows the old Via dei Carri (cart road): along this route alunite, the mineral from which alum was obtained, was carried to the Caulare area, where the processing tanks still survive, and then down to the port of Casamicciola. ### The fumaroles of the Rotaro and the coast Fumarolic activity can also be found on [Monte Rotaro](https://visitcasamicciola.com/en/nature/monte-rotaro-fumaroles/), along the Maddalena Trail, and on the eastern coast between Bagnitiello and Castiglione, where it seems to form a single system with the hot springs. In the past some fumaroles were harnessed in the “stufe”, the natural sweat rooms of the spa establishments. ## Casamicciola's four hydrothermal basins - **[Gurgitello basin](https://visitcasamicciola.com/en/thermal-spas/gurgitello-thermal-basin/)**, on the eastern side of Piazza Bagni, at the foot of the Ombrasco hill: seven springs with saline-bicarbonate-alkaline waters between 60 and 65 °C. In the 16th century the physician Giulio Iasolino called it the “queen” of the island's waters. - **[Cotto and Sinigallia basin](https://visitcasamicciola.com/en/thermal-spas/cotto-and-sinigallia-thermal-basin/)**, on the western side of the same square, with springs between 50 and 60 °C. - **[La Rita basin](https://visitcasamicciola.com/en/thermal-spas/la-rita-thermal-basin/)**, at the bottom of a ravine that forms part of an ancient crater, with waters between 60 and 72 °C. - **[Castiglione basin](https://visitcasamicciola.com/en/thermal-spas/castiglione-thermal-basin/)**, on the eastern coast, with springs emerging near the sea at around 70 °C. These waters gave rise to the town's spa vocation, as shown by historic establishments such as the [Antiche Terme Belliazzi](https://visitcasamicciola.com/en/thermal-spas/belliazzi-historic-thermal-spa/) and the [Antiche Terme Manzi](https://visitcasamicciola.com/en/thermal-spas/manzi-historic-thermal-spa/). ## Hiking tips Fumarole areas have hot and at times unstable ground: always stay on marked trails, keep away from the steam vents and wear hiking boots. The Alum Trail is about 8.4 km long and takes around three hours, starting from Fango and ending in Piazza Maio. ## Frequently asked questions ### Why are there thermal waters in Casamicciola? Because Ischia is an active volcanic area: heat from the deep magmatic system warms the water circulating underground. Where it finds fractures in the rock, it rises to the surface as hot springs. ### Where can you see fumaroles in Casamicciola? The best-known fumarole field is on Monte Cito, crossed by the Alum Trail. Other fumaroles are found on Monte Rotaro and along the coast between Bagnitiello and Castiglione. ### How hot are Casamicciola's springs? According to historical descriptions of the basins, the springs range from about 50 °C in the Cotto basin to 72 °C at La Rita. Temperatures vary from one spring to another, even within the same basin. ### Is it dangerous to go near the fumaroles? Steam from the most active fumaroles can approach 100 °C, and the ground may be hot or unstable. Always stay on marked trails and keep away from the vents. ## Also worth seeing - [Monte Rotaro Fumaroles](https://visitcasamicciola.com/en/nature/monte-rotaro-fumaroles/) - [Monte Cito Solfatara and Fumaroles](https://visitcasamicciola.com/en/nature/monte-cito-solfatara-fumaroles/) - [Gurgitello Thermal Basin](https://visitcasamicciola.com/en/thermal-spas/gurgitello-thermal-basin/) - [Cotto and Sinigallia Thermal Basin](https://visitcasamicciola.com/en/thermal-spas/cotto-and-sinigallia-thermal-basin/) - [La Rita Thermal Basin](https://visitcasamicciola.com/en/thermal-spas/la-rita-thermal-basin/) - [Castiglione Thermal Basin](https://visitcasamicciola.com/en/thermal-spas/castiglione-thermal-basin/) - [Antiche Terme Belliazzi](https://visitcasamicciola.com/en/thermal-spas/belliazzi-historic-thermal-spa/) - [Antiche Terme Manzi](https://visitcasamicciola.com/en/thermal-spas/manzi-historic-thermal-spa/) - [Alum Trail (Sentiero dell'Allume)](https://visitcasamicciola.com/en/nature/alum-trail/) - [The Volcanic Origins of Casamicciola](https://visitcasamicciola.com/en/history/volcanic-origins-of-casamicciola/) ## Sources and further reading - [Ischia – Dipartimento della Protezione Civile](https://www.protezionecivile.gov.it/it/approfondimento/ischia/) - [Il Sentiero dell'Allume – Ischia.it](https://www.ischia.it/sentiero-dell-allume) - [Ischia: i bacini idrotermali di Casamicciola – Hotel La Maggioressa](https://www.hotellamaggioressa.com/it/ischia/) - [Ischia – Storia eruttiva – Osservatorio Vesuviano INGV](https://www.ov.ingv.it/index.php/ischia-storia-eruttiva)