A Comprehensive Guide to Jellyfish in Greece

Key Species, Seasons, and Updated Safety Tips for 2025

Jellyfish in Greece Quick Facts

Jellyfish blooms in Greece are a recurring phenomenon, particularly in the warmer summer months.
The most significant species to watch for is the Mauve Stinger (Pelagia noctiluca), known for its painful sting. Other common types include the Moon Jellyfish and the harmless Barrel Jellyfish.
High-risk areas often include the Ionian Sea and parts of the Aegean Sea, with sightings being more frequent in late summer and early autumn.
If stung, the primary first aid is to rinse the area with seawater and apply a paste of baking soda and water or a commercial sting neutralizer. Avoid using fresh water.
Recent data from marine monitoring programs indicate increased sightings in certain coastal areas due to rising sea temperatures.

Jellyfish in Greece Key Species, Seasons, and Updated Safety Tips for 2025

Greece, with its stunning sapphire waters and sun-drenched islands, is a premier destination for travelers. However, its beautiful seas are also home to a diverse population of jellyfish. While most encounters are harmless, understanding the common species, high-risk seasons, and proper safety protocols is essential for a worry-free vacation. As of August 2025, marine experts continue to monitor changes in jellyfish populations, with a growing emphasis on proactive traveler education.

The Mauve Stinger (Pelagia noctiluca) remains a primary concern for beachgoers in Greece. As of August 2025, reports indicate a persistent presence, especially in the Pagasetic Gulf and its outlet into the Northern Evia Gulf. This phenomenon has also spread to the Northern Sporades, with verified sightings around popular islands such as Skiathos and Skopelos.

Travelers to the Ionian Sea and the Cyclades are also advised to remain cautious. While the severity may fluctuate, isolated appearances are still expected in these areas, and it's always best to check with local authorities for the most recent beach advisories.

Over the past few years, warmer-than-average sea temperatures have led to an increase in jellyfish blooms, particularly in the Ionian Sea and parts of the Aegean. This guide has been updated with the latest insights to help you navigate these beautiful waters safely.

The Main Players: Jellyfish Species in Greek Waters

1. The Mauve Stinger (Pelagia noctiluca)

The Mauve Stinger is arguably the most notorious jellyfish in the Mediterranean. It is a small but highly venomous species with a translucent, bell-shaped body that often has a distinct pink or purple hue. It's also bioluminescent, earning it the nickname "night-light jellyfish."

Sting Severity: Painful and causes a fiery, burning sensation. The sting can lead to red welts, blisters, and localized swelling. Allergic reactions are rare but possible.
Appearance: Its bell is typically less than 10 cm in diameter, with eight long tentacles and four frilly oral arms.
Season: While present year-round, massive blooms are most common from late spring to autumn, particularly after periods of prolonged calm weather.

2. The Moon Jellyfish (Aurelia aurita)

The Moon Jellyfish is easily identifiable by the four translucent, horseshoe-shaped gonads visible through its bell. It's a very common species found worldwide, including in Greek waters.

Sting Severity: Generally considered harmless to humans. Its venom is very weak and usually causes no more than a mild, tingling sensation that fades quickly.
Appearance: A clear, plate-like bell up to 40 cm in diameter.
Season: Most common in coastal waters during spring and early summer.

3. The Barrel Jellyfish (Rhizostoma pulmo)

This is one of the largest jellyfish found in the Mediterranean. It's also known as the Dustbin Lid Jellyfish because of its large size. Despite its imposing presence, it is a relatively benign species.

Sting Severity: Very mild. The sting is generally not painful to humans and can be described as a gentle stinging sensation.
Appearance: A large, solid, bell-shaped body that can be up to 60 cm in diameter. It lacks tentacles but has eight thick, frilly oral arms.
Season: More common in early summer but can be seen throughout the year.

4. The Fried Egg Jellyfish (Cotylorhiza tuberculata)

As its name suggests, this jellyfish looks like a fried egg floating in the water. It has a distinct yellow, central dome surrounded by a white bell.

Sting Severity: Completely harmless to humans. It has a symbiotic relationship with small fish, which often shelter beneath its bell.
Appearance: A flat, circular bell with a prominent yellow dome in the center. Its color and shape are unmistakable.
Season: Typically found in warm, calm coastal waters during late summer.

High-Risk Seasons and Coastal Hotspots

Jellyfish blooms are influenced by a combination of factors, including water temperature, currents, and wind. For a trip to Greece in 2025, it's particularly important to be aware of the following patterns:

Late Summer to Early Autumn: The period from July to September, when sea temperatures are at their highest, is when jellyfish are most active. This is the peak season for species like the Mauve Stinger.
Ionian Sea: The Ionian Islands (Corfu, Kefalonia, Zakynthos) have seen a notable increase in jellyfish sightings in recent years. This is due to specific currents that can push large swarms towards the shores.
Aegean Sea: While historically less affected by major blooms, parts of the Aegean, especially the coastlines of the Cyclades and the Sporades, have experienced occasional jellyfish blooms, often influenced by wind patterns.

Prevention and What to Do If You Get Stung

The best way to deal with jellyfish is to avoid them entirely.

Prevention Tips:

Check Local Warnings: Always look for warning signs or flags on beaches. Many organized beaches will have a flag system to alert swimmers to the presence of jellyfish.
Ask Locals: Lifeguards, hotel staff, and restaurant owners are excellent sources of information. Ask them about recent sightings before you enter the water.
Wear Protection: In areas known for jellyfish, consider wearing a rash guard, wetsuit, or a full-body swimsuit. This provides a simple but effective physical barrier.
Avoid Certain Times: Jellyfish often follow the sun and may be more visible in calm, shallow waters. Be especially cautious after a period of prolonged calm weather, as swarms can gather near the shore.

First Aid for a Sting:

If you are stung, stay calm and follow these steps:

Get Out of the Water: Exit the water immediately to prevent further stings.
Rinse the Area: Rinse the affected area with seawater. Do not use fresh water, as it can cause the remaining nematocysts to fire.
Apply Vinegar: If available, rinse the area with vinegar for at least 30 seconds. This is the most effective way to deactivate the stinging cells of most Mediterranean species, including the Mauve Stinger.
Remove Tentacles: Carefully and gently remove any remaining tentacles or stingers with tweezers. Do not use your bare hands.
Apply Heat: After rinsing and removing the tentacles, immerse the stung area in hot water (as hot as you can stand without burning) for 20-45 minutes. This helps to break down the venom and reduce pain. A hot pack or towel can also work.
Pain Relief: Over-the-counter pain relievers or antihistamines can help with pain and itching.
Seek Medical Help: If you experience severe symptoms like difficulty breathing, chest pain, swelling of the face or mouth, or if the pain is unbearable, seek immediate medical attention.