Submarine andesitic lava and pyroclastic rocks of Nisyros(24)

They can be found exclusively on the western coast. These mainly comprise a hyaloclastic agglomerate, with 40m maximum thickness.

It comprises blocks of basaltic andesite, with an average size of 10-15cm, bound by a yellow palagonitic cement, the result of glass alteration on the exterior surface of blocks, thanks to the rapid magma cooling after having outflow and fractured in shallow marine environment

. Deposits exhibit stratification, horizontal at the lowest parts, and at a slope gradient of 200-300 towards the top.

The pillow-shaped form is maintained in some cases where lava has not been fragmented, mainly at the base of the formation, with pillow diameters between 0.4 to 8m.

Underwater tuffs and tuffites mainly appear at cape Kanoni and further to the south; these are severely altered by fumarolic activity.