Diving means accepting that we are not owners of the sea, but guests. And rarely is this truth so evident as when we glide alongside a jellyfish, floating in the infinite blue.

Jellyfish and divers: a fascinating coexistence beneath the sea

When we think of jellyfish, we often imagine stings, burns, and a certain level of respect (or fear). However, in the world of diving, learning to coexist with them is part of the experience, teaching us far more than just marine biology: it teaches respect, adaptability, and wonder.

Ancient inhabitants of the ocean

Jellyfish have existed for over 500 million years, long before humans ever dreamed of exploring the ocean. Made mostly of water, their bodies drift with the currents, following a simple yet perfectly adapted life cycle.

As divers, we are only temporary visitors in their ancient home.

Unexpected encounters

During a dive, encountering jellyfish can be magical—or challenging—depending on the species and how we react. In places like the famous Jellyfish Lake in Palau, you can swim among thousands of golden jellyfish without fear of stings. In other places, like the Mediterranean in summer, species such as the Pelagia noctiluca require extra caution.

The key is to observe without invading: move calmly, maintain a respectful distance, and resist the urge to touch them—even if it’s tempting.

Why so many jellyfish?

Climate change, overfishing, and pollution have caused jellyfish populations to rise in many seas. Seeing more blooms during our dives is no accident: it’s a message from the ecosystem that we must learn to interpret.

As responsible divers, we must also recognize how our human activities impact the oceans.

The lesson from jellyfish

Swimming alongside jellyfish reminds us of a fundamental truth: Not everything in nature is meant to be conquered or controlled. Sometimes, the best way to interact is simply to float, observe, and be amazed.

In this coexistence, we learn patience, adaptability, and respect for life forms radically different from ours, yet equally essential to the balance of the planet.

Curious Stories:

In 2006, in Ireland, millions of jellyfish invaded a salmon farm, killing over 100,000 fish in just a few hours.

In Japan, the Nomura’s jellyfish (the size of a refrigerator) causes so many problems for fishing that specific programs have been created to hunt them.

1. The Wall of Jellyfish – Philippines

A group of freedivers exploring a reef came across what they described as a “living wall” of tiny jellyfish. They were packed so tightly together that it was impossible to avoid them. To get through, they had to swim slowly, carefully controlling their breathing to avoid disturbing them. Although most were harmless, some divers came out with slight skin irritations — but also with incredible photos!

2. Diving Among Giants – Japan

Off the coast of Japan, some divers have encountered Nomura’s jellyfish, massive creatures the size of a refrigerator and weighing up to 200 kilograms. Imagine being 10 meters underwater and seeing something the size of a small car approaching silently. They aren’t particularly aggressive, but their massive size and stinging tentacles require divers to maneuver very calmly and respectfully.

3. An Unexpected Swarm – Mediterranean

In areas like the Balearic Islands (where you also dive), there are times when ocean currents bring swarms of Pelagia noctiluca (the luminous jellyfish). An instructor shared that during a night dive, they turned on their torches and suddenly the water lit up with hundreds of bright purple dots: hundreds of fluorescent jellyfish! It was a stunning sight — although they ended the dive a bit earlier to avoid stings.

4. Jellyfish Lake – Palau

In this incredible place in Micronesia, an isolated marine lake is filled with millions of golden jellyfish that have lost their ability to sting. Freedivers and snorkelers can swim among them as if floating through a dream. It’s one of the very few places in the world where you can touch jellyfish without fear.

Tips for safe diving among jellyfish

1. Stay calm

If you see jellyfish nearby, avoid sudden movements. Swim slowly and watch the direction of the current to anticipate their drift.

2. Use protection

A neoprene wetsuit, even a thin one, can protect most of your body from accidental contact. You can also wear light gloves and booties.

3. Do not touch, even if they seem harmless

Some small or seemingly transparent jellyfish can still sting. It’s best to admire them without any physical contact.

4. Avoid dense swarms

If you see a very concentrated “bloom,” it’s safer to slightly change your course or ascend/dive to go around it.

5. Take care of your buddies

Stay attentive to your dive companions. A sting on the face, neck, or other sensitive areas may require immediate assistance.

6. Learn about local species

Get informed before diving about the common jellyfish species in the area. Some are harmless, others require more caution.

7. Carry a small first aid kit

Especially if you’re diving from a boat. Vinegar, salt water (never fresh water!), and tweezers to remove tentacle remnants can be very helpful.

8. Get trained in hazardous marine life first aid

Taking a course like DAN HMLI (Hazardous Marine Life Injuries) prepares you to recognize different types of injuries caused by marine life and respond appropriately in an emergency. An essential training for any responsible diver.