Jellyfish Lake (Rock Islands)

LakesKoror, Eil Malk (Mecherchar), Rock Islands, Palau

Fragile nature — stay on the trail, leave no trace.

August·Quiet month

May–Nov

Palau's wet season: thunderstorms build to a June–July peak, the rainiest months, and typhoons turn possible — most frequent August–November — roughening seas and sometimes disrupting boat trips; the golden swarm thins in warmer water but never leaves, and tours run year-round, so nothing closes.

Year-round Millions of golden jellyfish drift across the lake year-round, following the sun each day; warm El Niño years have twice collapsed the swarm before it returned.

Jellyfish Lake holds millions of golden jellyfish that pulse past your skin without a sting. Cut off from the open sea when rising water flooded this limestone basin some 12,000 years ago, the lake — known to Palauans as Ongeim'l Tketau — became a world of its own. Isolated from the fish and anemones that once hunted them, the golden jellyfish gradually gave up almost all of their stinging power, and today their venom is far too weak for a swimmer to feel. They live instead by farming sunlight: tiny algae inside their tissue feed them in return for light, which is why the whole swarm drifts across the lake each day, following the sun from one shore to the other. The lake lies on forested Eil Malk island, among the mushroom-shaped islets of the Rock Islands Southern Lagoon, a UNESCO World Heritage Site since 2012. A short, steep trail climbs the island's wooded spine and drops to a wooden dock at the water's edge. Slip in with a mask and the empty green gives way to a slow cloud of amber bells, thousands of soft bodies bumping and sliding gently past as you swim among them in warm, still water. Scuba tanks are banned here — partly to spare the jellyfish, and partly because a lethal layer of hydrogen sulfide lies below about 15 metres, in deep water that never mixes. The swarm is fragile in another way too: warm El Niño years have twice collapsed it to near zero, in the late 1990s and again after 2016, each time closing the lake until the jellyfish slowly returned. By 2026 they were back in force, their daily migration once more filling the sunlit water.

Worth knowing

Good to know

Snorkelling is the only way in — scuba diving is banned both to protect the jellyfish and because the lake's still, deep water turns dangerously toxic.
Come mid-morning to midday — when the sun is high the jellyfish crowd into the open, sunlit middle of the lake and thin out along the shaded edges.
Wear a rashguard instead of sunscreen — Palau bans reef-toxic sunscreens, and covering up protects both your skin and the lake's delicate balance.
Check the jellyfish forecast before you book — warm years have thinned the golden swarm to a few thousand, so confirm recent counts rather than assume a wall of millions.
Leave your fins on the boat — they are not allowed in the lake, where a kick can shred the fragile bells, so a slow breaststroke is all you need.

Things to do

1
Swim with the golden jellyfish
A short, steep trail crosses the wooded island and drops to a dock, and from there you snorkel out toward the middle of the lake. Within a few minutes you are inside the swarm: thousands of soft amber bells bumping and sliding past your arms and legs, in water that is warm and completely still. Their sting is far too weak for a person to feel. Fins are banned because a kick can tear the bells, and scuba tanks are not allowed, so the whole visit is a slow breaststroke on the surface.
2
Dive the manta ray channel
German Channel is a cut through the reef where manta rays come in to be cleaned, hanging almost still in the current while small reef fish pick parasites off their skin. Divers settle on the sand a little way off and wait, because the rays approach on their own and swimming at them drives them away. They come to feed as well as to be cleaned, so the odds are best when the tide is running and pushing plankton through the channel.
3
Drift over the Rock Islands' reefs
Beyond the lake, Palau's reefs rank among the richest in the Pacific. Snorkel over coral walls and gardens where clouds of fish part around you and reef sharks patrol the drop-offs beneath the limestone islets.
4
Kayak between the islands
The Rock Islands are hundreds of forested limestone knobs whose bases have been eaten away at the waterline, which is what gives them their mushroom shape. A kayak goes where tour boats cannot, slipping under those undercut rims and into coves and narrow channels between the islets, close enough to see the sponges and shells growing on the rock at eye level. The lagoon inside the reef is sheltered and shallow, so the paddling stays calm even when the open sea outside is not.
5
Rest on a deserted sandbar
As the tide falls, bars of white sand surface in the shallows between the islands, dry land for a few hours where there was open water before. Boats pull up alongside and you can stand in warm, knee-deep turquoise with nothing around you but the ring of green limestone islets. The tide decides how long the bar lasts, so trips are timed to it, and a late-afternoon stop ends with the sun dropping straight into the lagoon.

Watch

Nearby

3.2 km

Rock Islands (Chelbacheb)

Koror