Every Surfer’s Worst Nightmare: Why Jellyfish Are Taking Over Our Oceans

Every surfer has a worst nightmare. For some it’s a closeout set on a shallow reef. For others it’s a snapped leash and a long swim in. Some worry about sharks. But ask around any lineup and one answer comes up again and again: that sudden, searing whip across your arm or neck as you duck-dive straight into a jellyfish.

One moment you’re paddling out on a perfect morning. The next, your skin is on fire, red welts are rising, and you’re scanning the water wondering how many more are out there, knowing that if it’s a large cloud of jellyfish, you may well have to paddle through them to get back to shore.

If it feels like that’s happening more often, you’re not imagining it. From non-surf spots like Ibiza, Spain, to established surf towns like Bude in the UK, jellyfish are turning up in bigger numbers, more often, and in places they never used to be. So what’s going on beneath the surface? And what does it mean for those of us who spend our lives in the water?

Are jellyfish really increasing?

In many places, yes. Scientists call a sudden explosion in jellyfish numbers a “bloom”, and blooms are getting bigger and more frequent in several of the world’s seas.

The Sea of Japan has been hit by blooms of the giant Nomura’s jellyfish, each one up to two metres across and weighing as much as a fridge. They have clogged fishing nets and even forced power stations to shut down when they blocked cooling-water intakes. The Mediterranean now sees summer swarms that close beaches. The Black Sea, the Gulf of Mexico and stretches of the Australian coast all report similar trouble.

Jellyfish have been drifting through our oceans for more than 500 million years. They’ve survived every mass extinction on record. They are built to thrive when other sea life struggles, and right now, we’re giving them plenty of help.

Why are there so many jellyfish? The 5 main causes

There’s no single villain. Instead, a handful of human-driven changes stack up in the jellyfish’s favour, and they tend to reinforce each other.

1. Overfishing

Tuna, sunfish, some sharks and sea turtles all eat jellyfish. Smaller fish such as anchovies and sardines compete with jellyfish for the same food: plankton. When we pull these fish out of the sea faster than they can breed, jellyfish lose both their predators and their rivals.

Worse, once jellyfish take over, they eat fish eggs and larvae. That makes it even harder for fish populations to bounce back, and an ecosystem can get stuck in a jellyfish-dominated state.

2. Warming oceans

Many jellyfish species love warm water. Higher sea temperatures speed up their growth and stretch their breeding season. Their polyps, the tiny stage that clings to the seabed, release more baby jellyfish when the water heats up.

Warmer water also lets tropical species spread into regions that used to be too cold for them. With strong El Niño conditions forecast for 2026/27 (we wrote about what a Super El Niño means for surf in a recent blog), many coastlines could see warmer water than usual this season.

3. Pollution and “dead zones”

Fertiliser and sewage washing off the land and down our rivers flood coastal waters with nutrients. That triggers huge plankton blooms. When the plankton dies and rots, it strips oxygen from the water, creating low-oxygen “dead zones”.

Fish suffocate or flee. Jellyfish don’t. They can cope with oxygen levels that would kill most fish, so they move in and take over. This is one big reason river health and ocean health are so closely linked.

4. Docks, piers and plastic

Jellyfish polyps need a hard surface to attach to, and natural sandy or muddy seabeds don’t offer many. Humans have given them millions of new homes: harbour walls, piers, oil rigs, fish-farm cages, breakwaters and floating plastic.

Every piece of plastic drifting in the ocean is a potential jellyfish nursery. One more reason to keep it out of the water.

5. Hitchhiking on ships

Ships pump seawater into their ballast tanks in one port and dump it in another, sometimes on the other side of the world. Jellyfish and their larvae ride along.

The most famous case is the comb jelly Mnemiopsis. It arrived in the Black Sea from the Americas in the 1980s, found no natural predators, and exploded. The Black Sea anchovy fishery collapsed soon after.

Is it happening everywhere?

Scientists are still debating whether jellyfish are increasing worldwide.

Long-term records are patchy, because until recently nobody was counting jellyfish very carefully. Some research suggests jellyfish numbers naturally rise and fall in cycles of roughly 20 years, so part of what we’re seeing could be a natural peak. But many scientists believe human activity is playing a big part.

What is clear is that blooms are getting worse in specific regions, usually the ones where several of the pressures above overlap: heavy fishing, warm water, polluted rivers and busy shipping lanes. The good news hidden in that finding is that these are pressures we can do something about.

What it means for surfers: jellyfish in Bali and beyond

We are based in Bali, so we know this one first-hand. During the wet season, roughly November to March, onshore westerly winds push swarms of bluebottles onto Bali’s west-coast beaches, from Kuta and Seminyak up to Canggu. Some days the tideline is a carpet of little blue bubbles.

Fun fact: the bluebottle, or Portuguese man o’ war, isn’t technically a jellyfish. It’s a siphonophore, a floating colony of tiny organisms working together. Its trailing tentacles can stretch for metres and still sting long after it has washed up dead on the sand. Your skin won’t care about the technicality.

Wherever you surf, keep these patterns in mind:

• Onshore winds blow them in. Floating species like bluebottles drift with the wind, so a few days of onshores often means a few days of stings.
• Warm water brings more. Summer and unusually warm spells are peak jellyfish time.
• Check before you paddle. Washed-up jellyfish on the beach are a good sign there are more in the water. Ask the locals or lifeguards.
• Some are seriously dangerous. Most stings are painful but harmless. Box jellyfish and Irukandji, found in parts of tropical Australia and Southeast Asia, can be life-threatening. Know what lives where you surf.

How to avoid jellyfish stings when surfing

You can’t control the ocean, but you can stack the odds in your favour.

• Cover up. A long-sleeve rash vest or wetsuit is the single best defence. Tentacles can’t sting through fabric. Our eco rash vests are made for exactly this kind of day.
• Watch the beach. Washed-up jellyfish or bluebottles are your early warning system.
• Read the wind. After a run of onshores, expect company in the lineup.
• Duck-dive with your eyes open. It’s harder to dodge what you can’t see.
• Don’t touch stranded ones. Even dead jellyfish and detached tentacles can sting.

What to do if you get stung

First aid advice differs by species and by country, so always follow local lifeguard guidance where you surf. As a general guide:

1. Get out of the water calmly. Pain can make you panic, and panicking in surf is dangerous.
2. Remove any tentacles. Rinse with seawater, or lift them off with gloved fingers or the edge of a card. Don’t rub the area.
3. For bluebottles: soak the sting in hot water, as hot as you can comfortably bear, for around 20 minutes. Heat eases the pain.
4. For box jellyfish (tropical waters): pour vinegar over the sting for at least 30 seconds and get medical help straight away.
5. Skip the myths. Don’t use fresh water, alcohol or ice packs straight on the skin, and no, peeing on it doesn’t help.

Get emergency help immediately if the person has trouble breathing, chest pain, severe pain spreading through the body, confusion, or a sting covering a large area, especially if they’re a child.

What can surfers do about it?

Jellyfish blooms are a symptom. The real story is an ocean under pressure. The same things that make room for jellyfish – overfishing, warming water, polluted rivers and plastic – are the things that threaten every wave we love.

That’s why we started Indorider. Every board we sell is handmade in Bali, our fins are made from recycled plastic, our wax is 100% beeswax, and our apparel is organic cotton. And we give 5% of every sale to ocean and river clean-up charities around the world.

A few things every surfer can do:

• Pick up three pieces of plastic every time you leave the beach.
• Choose sustainably caught seafood, or eat less of it.
• Support groups cleaning up rivers, where much of the ocean’s pollution starts.
• Buy gear that’s built to last and made with the ocean in mind.

Healthy oceans mean fewer jellyfish swarms, more fish, cleaner water and better sessions for all of us.