What kind of lake is it?

A marine lake linked to the sea through rock

How do the golden jellyfish get much of their food?

From algae living in their tissues

Why can snorkelers swim among them?

Their sting is too weak to feel

Why is scuba diving banned in the lake?

A deep layer holds toxic hydrogen sulfide

Jellyfish Lake Quiz: Palau's Golden Jellyfish and Marine Lakes

This Jellyfish Lake quiz snorkels into a saltwater lake on Palau's Rock Islands where millions of golden jellyfish drift in the light. Play 10 interactive questions on how the lake formed, jellyfish that farm algae, their daily trip after the sun, a mild sting, the toxic deep layer, the 2016 drought crash, the reopening and sunscreen rules.

Start Jellyfish Lake Quiz

🎯 Daily Trivia Challenge • 🧠 10 Questions • ⏱️ 150 Seconds

Question 1 / 10 Time: 150s

Country
Which country is Jellyfish Lake in?
Islands
Which island group holds the lake?
Type
What kind of lake is it?
Jelly
Which jellyfish is famous there?
Food
How do the golden jellyfish get much of their food?
Sun
Why do the jellyfish migrate across the lake each day?
Sting
Why can snorkelers swim among them?
Deep
Why is scuba diving banned in the lake?
Crash
What caused the jellyfish numbers to crash in 2016?
Sunscreen
What has Palau done to protect reefs and lakes?

Explanations: answer key for all 10 questions

Q1: Which country is Jellyfish Lake in?
Answer: Palau
It is in Micronesia.
Q2: Which island group holds the lake?
Answer: The Rock Islands
They are limestone islands.
Q3: What kind of lake is it?
Answer: A marine lake linked to the sea through rock
Seawater seeps in through cracks.
Q4: Which jellyfish is famous there?
Answer: Golden jellyfish
It is a form of Mastigias.
Q5: How do the golden jellyfish get much of their food?
Answer: From algae living in their tissues
The algae need sunlight.
Q6: Why do the jellyfish migrate across the lake each day?
Answer: To follow the sunlight
Their algae need light.
Q7: Why can snorkelers swim among them?
Answer: Their sting is too weak to feel
Isolation weakened their stings.
Q8: Why is scuba diving banned in the lake?
Answer: A deep layer holds toxic hydrogen sulfide
Lower water has no oxygen.
Q9: What caused the jellyfish numbers to crash in 2016?
Answer: A drought linked to El Niño
Numbers later recovered.
Q10: What has Palau done to protect reefs and lakes?
Answer: Banned reef-toxic sunscreens
Rules began in 2020.

Golden Jellyfish That Chase the Sun

Jellyfish Lake, or Ongeim'l Tketau, lies on Eil Malk in Palau's Rock Islands. It is a marine lake, filled by seawater seeping through cracks and tunnels in the limestone, and it formed about 12,000 years ago as sea levels rose. The Rock Islands Southern Lagoon was listed by UNESCO in 2012.

Golden jellyfish, a form of Mastigias, evolved in isolation in the lake. Algae living in their tissues photosynthesize and supply much of their food, so each day the jellyfish swim across the lake following the sun. Their sting became so weak that snorkelers barely feel it.

Below about 15 m, the lake has no oxygen and holds toxic hydrogen sulfide, so scuba diving is banned. In 2016 an El Niño drought made the water warmer and saltier, and the jellyfish crashed. The lake closed, numbers recovered and it reopened in 2019. Palau banned reef-toxic sunscreens in 2020.

What This Quiz Teaches

Ocean and ecology fans will enjoy these questions.

How the lake formed
How the jellyfish feed
Why they migrate
Why diving is banned
What threatened them

Did You Know?

Visitors must kick slowly to avoid harm.
Moon jellyfish also live in the lake.
A steep trail leads over a ridge.
Permits are needed for the Rock Islands.
Mangroves line the lake edge.