Narrator: Some springs will eventually emerge in salt water - more than twenty miles off shore. Here, pirates once dropped buckets overboard. It's one of the very few places on earth where the sea provides drinking water.

The warm spring waters revitalize the barren sea bed in the Gulf of Mexico. And the rush of warmth allows for an oasis of life to flourish.

The water surges with the arrival of sardines - hundreds of thousands of them. With the cooling of the sea water in winter, sardines seek the fresh water baths for warmth. Their presence doesn't go unnoticed by predators--Amber Jacks.

The panicked sardines school for protection, each fish struggling to hide inside the shoal. Rapid maneuvers and shiny scales aim to confuse.

The Jacks rise from below, expelling air from their gills, in an attempt to contain the sardines.

Warm waters attract more than fish. They also entice the gentlest, quietest, and most peculiar mermaid of these waters, the Manatee.

For them, the springs are the difference between life and death. If the waters cool below 68 degrees Fahrenheit, manatees can die.

Manatees migrate to Florida every winter for the warmth they need, but double-crested cormorants live here all year round.

A manatee's life seems to be one of leisure. They spend much of the winter sleeping -surfacing to breathe without even waking up. Even the persistent pecking of Sunfish, who clean them of the algae growing on their skin, don't disturb their dreams.

Sunfish are everywhere here - and that's what draws the Great Blue Heron.

When it comes to fishing, Herons are masters of the waiting game.

Cormorants employ different tactics. They zero in on Sunfish that they know are grazing around manatees.

The heron needs only to wait patiently for its share.

Its patience is rewarded. The cormorant isn't so lucky. The water's crystal clearness works against it - fish can easily see it coming.

The cormorant stirs up the mud, clouding the clear water, and launches a surprise attack.

But it's the heron who ends up the winner.

The cormorant gives up, for now.

The bird has been foiled by the clarity of the water, the very thing that enables the manatee to thrive. The light through these waters helps plants flourish and manatees are strict vegetarians. They can eat a hundred pounds a day and can weigh more than a ton and a half.

Despite all the advantages of Florida's springs, manatees are still highly endangered. Boat propellers have killed many of them. Only about two thousand of these gentle creatures are left in Florida.

Following the manatee into the springs are salt water fish.

Mangrove snappers should not be able to survive in these fresh waters. But high calcium concentrations give the springs properties similar to saltwater. Lucky for the snappers, who can bask in these warm waters until winter lets up.

Snappers and manatees drift, suspended in time, in a winterless world.

The water is teeming with fish - but the eagle has a problem.

Being top predator means nothing if everyone can see you.

Underwater, Striped mullet harvest algae which grow on fields of eel grass.

If the mullet spot the eagle, they will dash for cover.

The clear waters have once again foiled a predator. The eagle comes up empty-handed.

The smaller osprey is also disappointed. As long as the eagle is around, the osprey can't fish without fear of being robbed.

Frustrated, he tries to chase the eagle away.

Undeterred, the eagle sets out again.

And finally, the osprey can catch a meal.

These two have found a way to overcome the challenge of hunting in these clear waters.

There's another predator here, too. When it shows up, everyone gets out of the way.

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