This is a chance to visit a beautiful island on the south of Kos Island. 
The small island, Nisyros, has been created by several volcanic eruptions that started 160.000 years ago. 
The center of Nisyros is dominated by a huge volcanic valley (a caldera). Its diameter is about 4km, which makes it the biggest caldera in Europe. 
The enormous crater in the valley is very fascinating. You can descend into the crater and admire the beautiful yellow sulphur crystal created by the sulphurous steam that escapes from holes in the bottom. 
After visiting the volcano, you have an hour free time in Mandraki, to wander around, visit the Monastery or do some shopping, enjoy a delicious bbq at Agios Antonios, and you have plenty of time to swim and sunbathe on the beautiful beaches, before getting back to the boat for the return trip to Kardamena harbor.

Meal: Pork & Chicken Souvlaki, Greek Salad, Tsatziki, Bread.