The closest beach to Kalamič (Sithonia) is Kalamitsi, just 150 m away. Within 15 km there are 30 beaches; below are the 12 closest to Kalamič, ordered by distance. Photos, map, reviews.
150 m from Kalamič

530 m from Kalamič

750 m from Kalamič

4.3 km from Kalamič

4.9 km from Kalamič

4.9 km from Kalamič

5.0 km from Kalamič

5.1 km from Kalamič

5.2 km from Kalamič

5.5 km from Kalamič

6.3 km from Kalamič

6.5 km from Kalamič

Kalamitsi, just 150 m from Kalamič. The rest are listed below, ordered by distance.
Within 15 km of Kalamič there are 30 beaches, with 69 across Sithonia in total.
Based on user reviews: Klimataria Beach (★5.0), Kalamičti Nudist Beach (★3.8), Kalamitsi (★3.5).
The beaches are spread out around Kalamič. A car makes exploring much easier — local buses and taxis are limited outside peak season.
Kalamič is on the Sithonia side of Halkidiki, in northern Greece. The nearest airport is Thessaloniki (SKG); from there a car is the most convenient way to reach the Sithonia villages.