Pristine waters teeming with marine life: a deep dive into the Greek island of Alonissos

The primary reason for the abundance and impressive size of fish, particularly the revered groupers, lies beneath the surface in the form of the National Marine Park of Alonissos Northern Sporades (NMPANS). Established in 1992, this pioneering initiative is not only Greece’s largest operational marine protected area (MPA) but also a beacon of successful environmental stewardship in the Mediterranean. While two larger MPAs have recently been designated elsewhere in Greece, their protective measures are yet to be fully implemented, making NMPANS a crucial living laboratory and a thriving example of conservation in action. The park spans approximately 2,220 square kilometres, encompassing Alonissos and six smaller islands (Peristera, Kyra Panagia, Gioura, Psathoura, Piperi, and Skantzoura), along with numerous rocky islets and sea rocks. Its comprehensive protective measures, including restrictions on fishing, boating, and development, have demonstrably fostered an environment where marine life can thrive unhindered. This is evidenced by the remarkable size, sheer abundance, and astonishing diversity of species observed within its glassy waters, which teem with colourful fish and precious shells, making swimming and diving here an absolute dream.

Beyond the vibrant reef life, Alonissos also holds deep historical secrets for those adventurous enough to explore deeper waters. The island is home to Greece’s inaugural underwater archaeological park and museum, centered around the awe-inspiring Peristera wreck. This ancient cargo ship, resting on the seabed off the islet of Peristera, dates back to the 5th century BC and offers a rare glimpse into ancient maritime trade. Its enormous cargo of amphorae – large ceramic jars used for transporting wine, olive oil, and other goods – remains remarkably preserved, scattered across the seafloor like silent witnesses to a bygone era. Access to this extraordinary site is strictly reserved for certified divers descending with accredited local dive centres, ensuring both the safety of the divers and the preservation of the delicate archaeological remains. My current expedition, however, is with one such reputable school, Ikion Diving, but today’s agenda involves something more accessible yet equally impactful.

We’ve gathered in the charming village of Steni Vala for the launch of a fascinating citizen science project, aptly named the Highly Protected Mediterranean Initiative. Far more engaging than its formal title suggests, this initiative sees Ikion Diving partnering with the distinguished Universities of Thessaloniki and the Aegean to offer free snorkelling and diving trips. The goal? To engage participants in logging both native and alien marine species, contributing invaluable data to ongoing ecological research. Initially, I confess to some apprehension regarding my fish identification skills, but the effervescent biologist Katerina Konsta quickly dispels any worries with an excellent, engaging briefing. We are each provided with waterproof dive slates featuring images of common and notable species to mark, a simple yet effective tool that imparts a delightful, almost childish sense of playing real-life scientist. This hands-on approach not only educates participants but also empowers them, turning tourists into temporary marine conservationists.

Paired up, as is customary, with Katerina herself – a stroke of luck for a solo participant like me – we embark on two gentle transects of the reef. The underwater world unfurls before us in a magnificent kaleidoscope of colours: vivid reds and deep blues, bright yellows, shimmering silver, and iridescent gold. Friendly little wrasse, intricately painted combers, sizeable parrotfish, and no less than 35 salema porgy gracefully accompany us, their presence a joyful challenge to my counting precision. Crucially, during our survey, there is no sign of any unwelcome invaders – no venomous lionfish, voracious rabbitfish, distinctive redcoats, or slender bluespotted cornetfish. These invasive species, largely having entered the Mediterranean through the Suez Canal (Lessepsian migration), pose a significant threat to native ecosystems, outcompeting local species and disrupting delicate food webs. Their absence here underscores the effectiveness of the marine park’s protective measures in maintaining ecological balance. Back at the dive centre, the data input process is swift and satisfying, and I am particularly gratified to find that my species card largely matches Katerina’s, give or take a particularly elusive grouper.

This experience has been immensely rewarding – a wonderfully gentle yet impactful introduction to marine fieldwork in what I am confidently declaring the best place in the Mediterranean to spot fish. This is not a statement I make lightly. Over several years, I have sailed extensively across the eastern Mediterranean, from Gibraltar all the way to Greece. My boyfriend, Wolfi, with his own extensive experience, sailed west from Turkey. Both of us are keen freedivers, and neither of us has witnessed such a vibrant profusion of marine life anywhere else. Wolfi, however, is reminded of particular stretches of the Turkish coastline from twenty years ago, where as a teenager, he regularly encountered now-rare giant triton snails (Charonia tritonis) and giant tun snails (Tonna galea). His recollections often spark a pang of envy in me, as I have never seen either of these magnificent molluscs in the wild until now. The presence of these iconic species, which have seen dramatic population declines across the Mediterranean due to overfishing and shell collection, is a strong indicator of the exceptional health of Alonissos’s marine environment.

With the satisfying glow of having contributed to something truly worthwhile, I wander down to Steni Vala’s charming harbour, where I find Wolfi soaking up the quintessential Greek island atmosphere. I can’t resist boasting about all the groupers I’ve meticulously counted. The harbour front is lined with inviting fish tavernas, but armed with a local’s discerning recommendation, we head for Tassia’s Cooking. (Should Tassia’s be fully booked, Sossinola is also an excellent alternative). Having spent the day making friends with so many fascinating fish, I find myself unable to contemplate eating one, so I opt for the comforting, homemade delights of creamy fava bean and vine leaves, followed by a richly layered moussaka. All are wonderfully priced and exquisitely prepared, reflecting the authentic culinary traditions of the island.

Just a five-minute stroll from Steni Vala’s bustling harbour, tucked serenely behind Glyfa beach, we discover our accommodation for the night: Ilya Botanic Suites. Nestled within a shady olive grove, these minimalist rooms offer a calming and compact retreat, their design thoughtfully reflecting the surrounding landscape. Fine-grained terrazzo floors are softened by elegant vertical wooden blinds and lush green plants, creating an organic aesthetic. The crowning jewel, however, is a small, private plunge pool, an utterly blissful amenity for sinking into after the "arduous" work of counting fish.

The following day, our exploration takes us north to Gerakas. Eager to dive back into the water, I’m submerged for less than a minute when my eyes catch a disturbing sight: a beautiful grouper, clearly distressed, snagged on the end of a tangled fishing line. Without hesitation, we retrieve some pliers and carefully work to free the struggling creature. Once released, it darts swiftly towards the protective embrace of the rocks, a powerful reminder of the delicate balance between human activity and marine life. This small act of rescue leaves a lasting impression. Afterward, we make our way to the tiny, picturesque port of Kalamakia, renowned for the excellent Margarita fish taverna, proudly owned by a local fisher. Our meal is a lavish affair, featuring fresh Alonissos tuna (Thunnus alalunga), succulent scorpionfish, and a delectable lobster. While the total, around €180 for two with drinks, is considered expensive by typical Greek standards, the unparalleled quality and undeniable freshness of the locally caught seafood make it an unforgettable gastronomic experience.

Away from the captivating blue of the Aegean, Alonissos reveals a surprisingly lush interior for an Aegean island. Unlike the often-arid landscapes of some Cycladic counterparts, Alonissos is verdant, adorned with fragrant Aleppo pines, majestic oaks, graceful maples, and ancient olive trees that stud its rolling hills. It even boasts a respectable mountain, Kouvouli, which, at 475 metres, offers panoramic views. The island, approximately 20 kilometres long, is easily traversable over a couple of days, and exploring its interior often means encountering more handsome goats than other humans. However, a word of caution for adventurers: some of the island’s roads only loosely resemble what one might call a "road," transforming into rugged tracks. For this reason, a quad bike is often preferable to a rental car if you wish to avoid losing your security deposit to an unexpected pothole or gravel patch. While there are numerous bike trails and beautiful ravine hikes, the searing July heat compels us to opt for the cool respite of shady forest walks and quick stops at dramatic clifftop viewpoints. Ultimately, on a Greek island in the height of summer, the best days, truly, begin and end in the refreshing embrace of the sea.

Happily, Alonissos offers a diverse range of beaches, accessible on both sides of the island, perfect for chasing breathtaking sunrise and sunset views. On the eastern shore lies the much-loved Agios Dimitrios, a sweeping, triangular stretch of pristine white pebbles. Well-organized with cafes and sunbeds, it’s a fantastic spot for families, though for me, its most stunning aspect is from above, where that distinctive tongue of white pebble plunges like an arrow into the luminous turquoise sea. Kokkinokastro, another beautiful beach, is famous for its striking red cliffs and ancient archaeological finds. Gialos, with its charming old windmill perched precariously on the cliffs, offers a wonderfully moody and atmospheric sunset. But my absolute favourite, hands down, is the small and wonderfully secluded Kremisma beach. It is, quite simply, absolutely beautiful. A short walk from a small car park leads to a slightly steep descent (it’s best to ignore the frayed rope that might offer illusory assistance), and crucially, there are no sunbeds, no bars, nothing at all – a true escape. It’s also rumored to be nudist-friendly, though for those unfamiliar with Greek customs, personally, I wouldn’t recommend stripping entirely.

Off the pebble shore of Kremisma lies a rocky coastline, a perfect habitat for spotting diverse marine life. Wolfi and I, by now, are engaged in a friendly competition of marine sightings. I’ve successfully spotted a baby moray eel and swooned over a shiny brown cowrie, but Wolfi remains ahead on octopus sightings. Competitive, me? Perhaps a little, especially when it comes to the wonders of the underwater world.

The busy little port town of Patitiri, where most visitors arrive, serves as the island’s main hub. It offers a plethora of accommodation options, diverse shopping, convenient beaches, a wide array of tavernas, and a local history museum (best visited in the cooler morning hours due to its steep climb). To truly grasp Alonissos’s profound importance in marine conservation, a visit to the monk seal information centre is essential. Run by MOm (the Hellenic Society for the Study and Protection of the Monk Seal), this centre sheds light on the plight of the Mediterranean monk seal (Monachus monachus), one of the most endangered marine mammals in the world. The marine park itself was primarily established to protect the dwindling population of these elusive creatures. The centre offers informative displays, engaging gifts, and captivating footage of seals in their natural habitat – though a sobering photo of a person with a nasty bite serves as a stark reminder of why close interaction with these wild animals should never be attempted.

For evening entertainment, don’t miss the tiny and eclectic Drunk Seal bar, which truly comes alive after midnight, offering a unique island vibe. Overlooking the port, you will find Kritamo restaurant, celebrated for its excellent cocktails and a sophisticated, contemporary spin on traditional Greek cuisine. Down among the vibrant throng of the town, the old-school taverna Archipelagos reliably serves up Greek classics – tender goat in tomato sauce, rich stifado – executed to perfection. A few kilometres along the coastline, the pretty harbours of Votsi and Rousoum Gialos are also well worth a leisurely stroll for a delightful dinner by the sea.

Behind and majestically above Patitiri sits Chora, the island’s historic hilltop "old town." This ancient settlement served as the island’s capital until it was tragically devastated by a powerful earthquake in 1965, leading to the establishment of Patitiri as the new administrative centre. Since then, most of the charming stone houses have been extensively restored, while several ancient churches and the original Byzantine walls remarkably survived the tremor. The village is beyond charming – a labyrinth of cobbled alleys crowded with candlelit tavernas, artisan shops, and balconies overflowing with vibrant bougainvillea. The panoramic views over both coastlines are simply spectacular, making it an ideal spot for enjoying a memorable sunset and dinner, with evening temperatures providing a welcome reprieve from the day’s heat, especially when navigating its steep streets. There’s also an innovative museum in Chora where landlubbers can "dive" the Peristera shipwreck using cutting-edge virtual reality technology, allowing them to virtually navigate the vast piles of amphorae without getting wet.

While the VR experience is great fun, one truly doesn’t need scuba skills or simulation to discover real treasures underwater in Alonissos. With Wolfi and I neck and neck in our competitive marine sightings, I conclude the week on an absolute high. My final, unforgettable encounters include spotting a stunning giant triton snail in the shallows, its magnificent shell a testament to its age, followed shortly by a rare giant tun snail, partly buried in the soft sand. The populations of both these majestic gastropods have plummeted across the wider Mediterranean due to relentless overfishing and indiscriminate shell collection. To witness them alive and thriving in Alonissos’s practically pristine waters is not just a joy, but a profound validation of the island’s unwavering commitment to marine conservation, solidifying its reputation as a true underwater paradise and a beacon of hope for the future of the Mediterranean’s biodiversity.

Practical Information:

Ilya Botanic Suites in Steni Vala offers double suites with a hot tub and garden view from approximately £105 a night. For free scuba diving and snorkelling trips to take part in a reef check in Alonissos, contact Kostas at [email protected] or check the Ikion Diving website (sporadesdiving.gr). Return ferry tickets to Alonissos from Skiathos cost about £45. Alternatively, ferries depart from Volos, Thessaly (a 2.5-hour drive from Thessaloniki), or Mantoudi, Evia island (a 2-hour drive from Athens, connected by a bridge), with tickets costing approximately £80.