Alonissos National Marine Park

Patitiri, Alonissos · Northern Sporades · Greece

The Alonissos National Marine Park is the largest marine protected area in the Mediterranean, encompassing over 2,200 square kilometres of pristine Aegean Sea around the Northern Sporades archipelago. Established in 1992 to protect the critically endangered Mediterranean monk seal, the park offers diving in waters that have benefited from decades of careful protection. The diving spans multiple sites around uninhabited islands dotting the archipelago. The reef systems are visibly healthier than at more touristed Greek islands. Hard and soft corals cover rocky substrates in dense formations, with red coral present below 25 metres. Groupers, increasingly rare across the Mediterranean, are present in encouraging numbers, holding territory with the confident curiosity that comes from living in protected waters. Schools of sea bream and barracuda patrol reef edges, and octopuses occupy practically every suitable hole. The park's seagrass meadows are among the Aegean's finest. Dense beds of Posidonia oceanica stretch across sandy areas between reef sections, providing nursery habitat for juvenile fish. Swimming over these underwater meadows, the density of life is immediately apparent — seahorses, pipefish, and cuttlefish all use the seagrass as cover. The possibility of encountering a Mediterranean monk seal adds anticipation to every dive. With only around 700 individuals remaining worldwide, these are among the rarest marine mammals on Earth. The park protects an estimated 50 to 80 seals that use sea caves around Piperi and other islands. While sightings during dives are uncommon, the knowledge that you are diving in monk seal habitat adds weight and meaning to the experience. Beyond natural history, the park contains several ancient shipwrecks speaking to the region's importance as a maritime crossroads. Diving at Alonissos is about experiencing the Mediterranean as it once was — healthy, abundant, and wild — in a place where thoughtful protection has allowed nature to maintain the upper hand.