Zakynthos is a land-based Ionian dive and snorkel destination built around short boat runs, cave light, loggerhead turtle conservation, and non-diver friendly beach time. Divers usually work from Keri, Agios Sostis, Laganas, or Kalamaki for morning trips to Keri Caves, Marathonisi, reef walls, arches, and shallow training sites. Freedivers get calm-water line sessions and photogenic cave swims, while snorkelers can join turtle-respectful boat trips around Laganas Bay, Keri Caves, and Marathonisi. The National Marine Park of Zakynthos is central to planning: turtles are protected, nesting beaches have strict day-use rules, and boats must follow park zones. Come June to September for the easiest sea conditions, with September offering warm water and fewer peak-summer crowds. Topside, add Blue Caves, Bochali, Zakynthos Town, olive groves, wineries, and current safety checks before planning around Navagio.