Santorini IS a volcano, and this is the only way to stand on it. A traditional wooden caique departs the Old Port (right below the tender pier) for the still-active crater island of Nea Kameni, where you hike about 90 minutes across steaming red-black lava fields to the summit craters, then sail to Palea Kameni to swim in the iron-rich warm hot springs. It is the lowest-cost, highest-payoff marquee experience on the island and the easiest to slot into a port day.
What to expect
You'll board a traditional wooden caique from the Old Port—just steps below the tender pier—and sail to the still-active volcano island of Nea Kameni. There, you'll hike roughly 90 minutes across steaming red-black lava fields to reach the summit craters, walking on the volcano itself and witnessing its raw, otherworldly geology up close. After descending, the boat sails to Palea Kameni, where you'll swim in warm, iron-rich hot springs that feel almost medicinal, turning the excursion from a geological marvel into a complete sensory experience. The entire outing takes about 3 hours, leaving plenty of daylight and margin to return to the ship.
This is the closest-priced category, so be honest: the ship's volcano-and-hot-springs boat tour is ~$70-$82 per person, only modestly above the ~$40-$60 all-in you'll pay direct. You still save ~$20-$40 per person booking direct, and because it leaves from the Old Port directly under the tender pier it doubles as the safe, near-port option if you don't want to commit to a long inland tour.
Good to know
The caiques depart directly from Fira's Old Port, eliminating the need for a tender or long transfer—critical on a 6–8 hour port day—and Caldera's Boats has been running this route since 1968, so timing is reliable. Book the tour in advance online or grab a spot at the pier if you want to avoid ship-tour markup (~$20–40 per person saved). Wear sturdy, closed-toe hiking boots for the lava-field walk, bring reef-safe sunscreen and a towel for the springs, and plan to be back aboard at least 45 minutes before all-aboard; the low price and proximity to the port make this the safest high-payoff volcano experience if you're wary of committing to a longer inland adventure.