"Is your air on?" asks Josh.
"Is your air on?" asks Anne. "Okay, let's go!"
Today Josh and Anne are taking us on a scuba-diving adventure near the Similan Islands in Thailand.
The water here is so clear that we can see things thirty meters away, and that's pretty far for being underwater!
Whenever people go scuba diving, they swim in a group for safety, so we had better stay together!
There are hundreds of great places to scuba dive in the world, and each of them is different.
Some places are very cold, or are filled with seaweed, or have only very small animals.
The Similan Islands, however, are great because the water is 28 degrees Celsius and crystal clear, and there are lots of big fish.
In fact, look over there! Josh has found a moray eel hiding in the rocks.
Don't worry; it is more frightened of us than we are of it.
Look at its sharp teeth!
It has two sets of jaws to pull its prey in, so keep your hands far away!
Eels aren't very friendly creatures, as you can tell, and they mostly live alone.
So we probably won't see another eel for quite a while.
Did you know that there are hundreds of plants that live underwater?
Thailand has many kinds.
One plantlike creature is called coral, and there are two kinds: hard coral and soft coral.
A coral is built from live cells that stack on top of each other in layers.
When the outer layer gets old, a new layer of cells forms around it so the plant grows taller or wider.
Like their names suggest, hard coral is stiff, while soft coral is able to sway with the ocean current.
Both soft and hard coral grow very slowly.
Look, this fan coral grows about one centimeter each year, so Anne is careful not to touch it as she swims by.
Touching a coral can kill it, and sometimes it can hurt us too so we stay far away.
Look, down at the bottom—there's a whale shark, the biggest fish in the world!
Anne is trying to get her picture taken with it, but don't worry, this shark won't bite.
Whale sharks only eat small animals and tiny plants that float in the water called plankton.
Still, we're careful not to disturb the shark since this is its home.
Josh is checking his pressure gauges, and signals to Anne that he is almost out of air.
Men use up air faster than women because their lungs are bigger and because they have more muscle,
but I think we have enough time to look at just a couple more creatures.
Oh no, Anne is giving the danger signal! She found a sea snake.
This underwater creature may be tiny, but its venom is twenty times more poisonous than any snake on land!
It eats mostly small fish by paralyzing them first with one quick bite.
It takes less than a second for its venom to work.
The sea snake seems to be a little hungry, so we'll move on.
Here is Josh's favorite animal, the cuttlefish.
Many people eat cuttlefish thinking it is an ordinary squid, but it is really an amazing animal.
Watch carefully. The mother cuttlefish is trying to protect its baby by distracting us.
See how its skin is changing colors so that we can see it better?
Cuttlefish can change the color and texture of their skin to match anything around them.
For example, if there is a field of black rocks nearby, their skin will turn bumpy and black.
If they swim by green seaweed, they will turn smooth and green.
If you put down a purple polka-dot blanket, their skin will have polka dots!
It looks like Josh is low on air.
It's time to return to our own world above-water, but don't be disappointed.
There will always be another adventure!