From the boat, Nisyros is just a dark cone in the sea, an hour from Kos.
From Nikia you look into the caldera – and at the pale patch in its middle.
Down at the rim it smells of sulfur and the ground hisses. You walk in. Without a guide.
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from the boat into the crater
The crater is open. There is no alert level, no reservation, no online ticket and no guide requirement: you drive to the parking lot on the crater rim, pay €5 at the booth – if it is staffed – and walk down the stepped path. According to the University of Athens (NKUA), seismic activity in 2026 is “almost non-existent”. The only rule is on the crater floor: the ropes around the mud pools and the thin crust.
260 × 350 m (850 × 1,150 ft), 27 m (90 ft) deep, 5–10 minutes down. Travel reports up to August 2026 describe it as walkable; the last documented closure was in early 2003 after a phase of unrest. If you only look from the rim, you pay nothing.
Next to the parking lot, staffed only while the excursion boats from Kos are on the island – roughly 10 am to 3 pm. Early in the morning and in the evening the access is unattended and in practice free. No cards, no online ticket, no official child rate.
The free municipal bus runs Mon–Sat at 8:00 am, 12:30 pm and 7:00 pm from Mandraki via Pali and Emporeios to Nikia – not into the caldera. To the crater you take the travel agencies' buses (from €8), a taxi or a rental scooter.
Since 2026 Nisyros has formally been part of the UNESCO Global Geoparks network (decision fall 2025): 481 km² (186 sq mi) including the islets Gyali, Pacheia, Pergousa, Strongyli and Kandeleousa. Ten marked geo-routes, no escort required.
Photo: Ввласенко · CC BY-SA 3.0
Stefanos is not a crater to look at but to walk into. The floor is flat, pale and warm, in places so hot that flip-flops come apart. Steam above 100 °C (212 °F) hisses out of holes, and yellow sulfur crystals grow around them. In the hollows behind the ropes the mud pools boil. It smells of rotten eggs, and the smell stays in your clothes.
Between 10:30 am and 3 pm you share the crater with the excursion boats from Kos. Before and after, you usually have it to yourself – the booth and cantina are closed then, and the access is open. If you stay overnight you get both: the empty crater in the morning and Nikia in the evening, the village on the caldera rim with the pebble-mosaic square and the volcano museum in the old school.
To be honest: there is no lava here. The last explosion was in 1888, a steam explosion without magma. What Nisyros offers is a hydrothermal system you can touch – and the certainty that beneath the pale floor the temperature is above 350 °C (660 °F). In completely still air, heavy CO₂ collects in the deepest hollows; dizziness is the signal to climb back out.
Affiliate links to GetYourGuide: if you book, we earn a commission and the price stays the same. Prices and ratings as of 22 September 2026. The €5 crater fee is not included in any offer – it is paid in cash on site. In a strong meltemi wind the small excursion boats are cancelled.
Photo: S.Nikolakakos · CC BY-SA 4.0
Nisyros has fewer rules than any Italian volcano. That is exactly why you have to know them yourself.
Cash at the ticket booth next to the parking lot; no card payment documented. If nobody is there, the access is open. No source names a child rate – on the Kos boats children aged 3–13 pay half price.
The crust is thin in places, the mud pools boil at over 100 °C (212 °F), and scalds leave chemical burns. The barriers are the only rule in the crater – and they are meant seriously.
Heavy CO₂ collects at the bottom of the deepest spots. In completely still air do not linger there; dizziness means: climb out. People with asthma or heart conditions keep the visit short.
No shade in the crater, above 35 °C (95 °F) in high summer. The ground is hot and the crust is sharp – closed shoes with a thick sole. At least a liter of water per person; the cantina closes when the boats leave.
| Admission Stefanos crater (descent), cash at the booth · view from the rim free | €5 |
| Volcanological Museum Nikia (travel guide figure 07/2026) | €4 |
| Municipal bus Mandraki–Pali–Emporeios–Nikia (not to the crater) | free |
| Volcano bus tour from the port of Mandraki, 2 hours, without crater admission | from €8 |
| Boat Kardamena–Nisyros round trip / volcano bus on Nisyros (Ticket Travel Kos) | €20 / €10 |
| Full day trip from Kos with hotel transfer, boat and bus (Kos4all) | €30 |
| Scheduled ferry Kos town–Nisyros, foot passenger, from | €6 |
Photo: S.Nikolakakos · CC BY-SA 4.0
Three ports on Kos, three different excursions. And on the island itself the question of how you cover the 13 km (8 miles) from the port into the caldera.
Excursion boat daily at 9:30 am, back at 3:30 pm; Mon/Tue/Thu/Fri additionally at 12:00 pm with return at 6:30 pm. Boat €20, volcano bus on Nisyros €10, children 3–13 half price. Roughly May to October; cancelled in strong wind.
Dodekanisos Seaways catamarans in about 50 minutes, Blue Star “Diagoras” in about 1 h 15, from about €6. Year-round, but not always out and back on the same day – the best choice if you stay overnight.
Kamari Boats on Tuesdays and Saturdays at 9:45 am (according to a travel forum, no published schedule). Irregular; the alternative is Kardamena, about 25 km (15 miles) away.
Paved road Mandraki–Emporeios–caldera, 25 minutes. Volcano bus of the travel agencies after the ferry arrives (from €8, 45 minutes at the crater), taxi, or rental scooter/car from about €25 a day. Or the municipal bus to Nikia and the trail down on foot, 45–60 minutes.
Photo: Ввласенко · CC BY-SA 3.0
Without a car: No airport. Ferries from Kos town (Dodekanisos Seaways about 50 minutes, Blue Star about 1 h 15, ANE Kalymnou), excursion boats from Kardamena (9:30 am/3:30 pm daily, additionally Mon/Tue/Thu/Fri 12:00 pm/6:30 pm) and from Kamari/Kefalos (Tue/Sat 9:45 am); also connections from Rhodes, Tilos, Kalymnos and Piraeus (Blue Star, several times a week). On the island: free municipal bus Mandraki–Pali–Emporeios–Nikia (Mon–Sat 8:00 am, 12:30 pm, 7:00 pm), volcano buses of the travel agencies after ferry arrivals, taxis, scooter and car rental in Mandraki.
By car: Rental car/scooter from Mandraki; the road Mandraki–Emporeios–caldera–crater is paved, about 13 km / 8 miles, 25 minutes. Parking lot on the crater rim next to the booth and cantina. Taking a rental car from Kos only with the rental firm's consent and on a car ferry (Panagia Skiadeni, Blue Star).
May/June and September/October: warm but still bearable in the shadeless crater, clear views from Nikia into the caldera, boats from Kos run daily. At the crater before 10:30 am (before the Kos boats arrive) or after 3 pm – then you are almost alone, though the booth and cantina are usually closed. Avoid midday in July/August (above 35 °C / 95 °F on the crater floor); in winter the island is quiet, ferries are rarer and the museum is partly closed.
Photo: Tomisti · CC BY-SA 4.0
The second way to get here: sailing and motorboat tours that combine Nisyros with Gyali and Agios Antonios. Less time at the crater, more time in the water.
Affiliate links to GetYourGuide: if you book, we earn a commission and the price stays the same. Prices and ratings as of 22 September 2026.
Photo: Ввласенко · CC BY-SA 3.0
Yes. A stepped path leads into the Stefanos crater, 5–10 minutes down, without a guide and without a reservation. On the crater floor the mud pools and areas of thin crust are roped off – beyond the ropes is off limits.
€5 per person, cash at the ticket booth next to the parking lot on the crater rim, as of 2026. The booth is staffed only while the excursion boats from Kos are on the island; if you only look from the rim, you pay nothing.
From Kardamena about 7 hours: departure 9:30 am, an hour's crossing, bus to the crater, Nikia, Mandraki, return at 3:30 pm. The scheduled ferry from Kos town takes 50 to 75 minutes but does not always return the same day.
Yes, and it is worth it: with the scheduled ferry from Kos town, a night in Mandraki and a rental scooter (from about €25) you have the crater to yourself before 10:30 am and after 3 pm. The free municipal bus takes you to Nikia; from there you walk down.
Yes, but dormant: the last steam explosion was in 1888, followed by phases of unrest in 1996–98 and 2001–02. According to NKUA, seismicity in 2026 is close to zero; Greece has no official volcano alert level like Italy's.
On Nisyros. The Stefanos crater is walkable, steams and smells; on Santorini the caldera is the backdrop, and the volcano itself sits on the island of Nea Kameni off the coast. Both belong to the same South Aegean volcanic arc.
€5 per person, cash at the ticket booth next to the parking lot on the crater rim. The booth is staffed only while the excursion boats from Kos are on the island (about 10 am–3 pm); if you only look from the rim, you pay nothing.
No. The crater is freely accessible; day trips from Kos come with an escort, independent travelers walk down on their own. Rope barriers around the mud pools and thin crust are the only rule.
Easiest by excursion boat from Kardamena (daily 9:30 am, back 3:30 pm; Mon/Tue/Thu/Fri also 12:00 pm/6:30 pm; €20 plus €10 volcano bus), from Kefalos/Kamari on Tuesdays and Saturdays at 9:45 am, or by scheduled ferry from Kos town (Dodekanisos Seaways about 50 minutes, from about €6).
The descent takes 5–10 minutes, and you stay 30–60 minutes in the crater; bus tours from Mandraki allow 2 hours, 45 minutes of which at the crater. A day trip from Kos takes about 7 hours including Mandraki and Nikia.
Yes, with supervision: short stepped path, flat floor, but boiling mud pools and hot ground beyond the ropes. Children 3–13 pay half price on the Kos boats; no source gives a child rate at the crater.
Sturdy closed shoes (flip-flops come apart on the hot ground), hat, sunscreen and plenty of water – there is no shade in the crater, and in high summer it is above 35 °C (95 °F). The sulfur smell clings to clothing.
An eruption is not foreseeable according to the monitoring (last steam explosion 1888). What is dangerous: scalding at mud pools above 100 °C (212 °F), breaking through the thin crust, CO₂ pooling in hollows in still air, and heatstroke. If you stay behind the ropes and do not come at midday, you are safe.
The free municipal bus runs Mon–Sat at 8:00 am, 12:30 pm and 7:00 pm from Mandraki via Pali and Emporeios to Nikia – not to the crater. To the crater you take the travel agencies' buses (e.g. €8 from the port), a taxi or a rental scooter/car; from Nikia a trail leads down.
Before 10:30 am or after 3 pm, when the Kos boats are not there; in summer generally early or late because of the heat. Best months May/June and September/October.
The historic municipal bath Loutra near Mandraki (water up to 46 °C / 115 °F) is restored but not yet in operation. You can bathe for free at the hot springs in the sea near Pali (Thermiani, 33 °C / 91 °F) and in Avlaki bay (up to 59–61 °C / 138–142 °F), where the water runs straight into the sea.
The University of Athens (NKUA) has run a seismometer network on the island since 2023, since July 2026 with a permanent station in Emporeios in the national network; the Institute of Geodynamics of the National Observatory of Athens brings together seismic, GPS/InSAR, gas and thermal data. There is no official volcano alert level as in Italy.
Sources · accessed on 22 September 2026
