Beyond lying on a beach, Halkidiki's clear water and scattered islets make it a strong base for boat trips, diving, and sailing.
The only inhabited island off Halkidiki's coast, Ammouliani is reachable by a short ferry from Trypiti or Ouranoupoli and offers sandy beaches, a fishing-village atmosphere, and views back toward the Athos peninsula. It's an easy half-day or full-day trip, often paired with a stop at the nearby uninhabited Drenia islets for snorkeling.
Sithonia's rocky coves and clear visibility have made it one of northern Greece's more established diving spots, with local operators running beginner try-dives and certified dives to underwater rock formations and the occasional wreck. Water stays warm enough for comfortable diving from June through September.