The geomorphology of Halkidiki is extremely interesting.  

It resembles  an inclined geological level, while moving from western to eastern. Thus, in Kalamaria (western side) and in Kassandra we find most of the plains, which are,  also, its most fertile regions. In the central region there are raised the mounts of Hortiati (1201 m.), of Holomontas (1165 m.) and of  Itamos (in Sithonia, 811 m.) and in the eastern point the splendid mountainous mass of mount Athos(2033 m)  .

The three peninsulas, that give the impression that  stick out from the Aegean Sea, make Halkidiki  the prefecture with the biggest length of coastlines in the continental Greece.  

The coastline of  Halkidiki  exceeds the 500 km, including every type of landscape. From the vast sandy beaches of Kalamaria, Nikitis, Toronis and Ierissos, to the  rocky and  woody sandy beaches of Sithonia, and from there to the graphic gulves of Vourvourou.  

Halkidiki does not have rivers, and this is one of the reasons why the sea that encircles  it is one of the  cleanest of Greece.