The closest beach to Ierissos (Athos) is Komitsa, just 480 m away. Within 15 km there are 15 beaches; below are the 12 closest to Ierissos, ordered by distance. Photos, map, reviews.
480 m from Ierissos

690 m from Ierissos

840 m from Ierissos

1.2 km from Ierissos

2.2 km from Ierissos

4.6 km from Ierissos

4.8 km from Ierissos

5.0 km from Ierissos

5.5 km from Ierissos

9.3 km from Ierissos

10.8 km from Ierissos

11.6 km from Ierissos

Komitsa, just 480 m from Ierissos. The rest are listed below, ordered by distance.
Within 15 km of Ierissos there are 15 beaches.
Based on user reviews: Trypiti (★4.5), Komitsa (★4.2), Ierissos Beach (★3.8).
The beaches are spread out around Ierissos. A car makes exploring much easier — local buses and taxis are limited outside peak season.
Ierissos is on the Athos side of Halkidiki, in northern Greece. The nearest airport is Thessaloniki (SKG); from there a car is the most convenient way to reach the Athos villages.