This time on Jonathan Bird’s Blue World,
Jonathan investigates what might be the clearest water in the world! Hi I’m Jonathan Bird and welcome to my world! Scuba divers crave clear water. Good visibility makes diving more like flying,
being able to see your surroundings from above. Humans are visually oriented. We like being able to see what’s going on
around us, and clear water allows us to keep a safe distance from something like feeding
sharks, but still see the action. Temperate water is rarely very clear. We consider ourselves lucky to get 30 feet
of visibility in New England. Sometimes it’s not even that good—more
like 10 feet. You can barely see anything until you are
right on top of it. Plankton makes this water extremely fertile,
but you can’t see through it very well. In the tropics, water has less plankton and
it’s often quite a bit clearer. It’s not unusual to have 100 feet, sometimes
even 150 feet of visibility in the tropics. At the massive Neutral Buoyancy Lab in Houston—a
huge indoor swimming pool where astronauts are trained—I have experienced visibility
of at least 400 feet. The water is so clear, it’s like it’s
not there at all. But this is a pool. The water is filtered and chlorinated. Is there anyplace in the world with naturally-occurring
clarity like this? To find out, I have come to Iceland. To a place called Silfra. Iceland is right smack-dab in the middle of
the mid-Atlantic ridge, where two large tectonic plates meet. Lava coming out from between these plates
at a hot spot created Iceland about 20 million years ago. But since those tectonic plates are still
moving, Iceland has cracks down the middle and occasional earthquakes as a result. This is one of the few places in the world
where you can actually see the crack between two tectonic plates! Silfra is one of those cracks. It has filled with spring water that percolates
up through the ground from distant glaciers. So it’s cold and it’s clear. Iceland itself is a beautiful and sparsely
populated country full of natural wonders. It has huge glaciers. And those glaciers give birth to icebergs
which float away into the North Atlantic ocean. But even though it’s called Iceland, it’s
not all ice by any means. At least in the summer. There aren’t many trees, but the landscape
features rolling green grassy hills. There are grazing sheep. And lots of farms. Summer meltwater feeds scores of rivers and
streams. Some are crystal clear, others are filled
with minerals making them milky white. And there are waterfalls. I mean a lot of awesome waterfalls! This is Gulfoss, one of Iceland’s largest. Until recently, the only divers who came here
were animals. But Silfra has changed all that. Divers now come from around the world to experience
the amazing visibility in this tiny dive site just a few meters wide and a few hundred meters
long. They say this is the clearest water in the
world. Let’s go find out! My adventure begins in downtown Reykjavic,
Iceland’s capital city. I head on over to Dive Iceland to sign up
for one of their all-inclusive Silfra dives. The next morning at the crack of dawn, I head
over to the dive site. We’re meeting early so we can have the whole
place to ourselves. Christine, Cameraman Todd and I meet up with
our divemaster, Jose Soroa, who gives us a basic introduction to the area and how we
will conduct the dive. We take a walk all the way around the site. Diving here is not without difficulty. I’ll need a dry suit to stay warm in the
water which is barely above freezing. Since most people don’t go to Iceland specifically
to dive, they often don’t bring any gear. Dive Iceland supplies everything you need,
even the dry suit. Our team has decided to try their gear, for
the full experience. So we’re all getting into drysuits we’ve
never worn before. After we have our suits on, I have to carry
my camera all the way from the parking area to the entry point. They could have put the parking area a little
closer! It takes us a few more minutes to get the
rest of the gear on, and then we hoof it over to the entry. Fortunately, the entry is easy. There’s a nice staircase right down to the
water. Jose hands me my camera and I sink down into
clear, cold water. While I get my gear adjusted, Christine and
Todd climb carefully down the steps to join me. Under the surface, there is nothing to see
but bare rock—and crystal clear water. My first view under the surface blows my mind—I
can see all the way down to the end of the crack where it takes a turn! I have no idea how far that is. Once everyone is ready, we submerge. Then Jose leads the way downstream. There’s a gentle current in Silfra from
the spring opening all the way down to a lake. The incredible visibility is no exaggeration! This is the clearest water I have ever seen
in sunlight. The straight sections of Silfra aren’t even
long enough to test the full visibility, but it’s easily many hundreds of feet. We swim for a few minutes through a narrow
crack, which is at least 50 feet deep. There’s nothing to see down there, so we
stay pretty shallow where the marginal morning light is a little better. Then we have to cross a shallow area to keep
going. In places it’s only two feet deep! I could get up and walk! I have no idea where we are heading but I
follow Jose because he has done this dive several hundred times. In this shallow water, strands of green algae
thrive on the ample summer sunlight. After passing through the shallow section,
we head into another deep crack. Now that the initial excitement has worn off,
I’m noticing the water temperature, which is only 36° Fahrenheit, barely above freezing. My face is completely numb. This water is nearly as cold as the water
in Antarctica! It might look tropical because of that blue
color seen in very clear water, but I’m definitely not in the Bahamas. I’m not going to let the cold keep me from
having some fun though! There might not be much to see, but I can
always use some nice clear water to practice blowing bubble rings. But it’s not easy with a tight hood and
numb lips! Everyone is getting pretty cold, so we continue
on. If we want to get out of this water, we need
to make it to the exit point, so we have some more swimming to do. At the end of the second section of deep water,
there is a wonderful sandy slope leading back to the shallows. We swim up it, expecting the water to get
warmer as we swim towards the sun, but alas there’s no thermocline. It’s just as cold at the top! We emerge up into what looks like a small
pond. The pond is actually an inlet from a huge
lake. Once the water goes out into the lake, it
loses its clarity. But here in this pond-like section, we get
our chance to see a long way underwater in a straight line. Finally we can see the steps for the exit,
and we swim over, with our fingers and toes totally numb. I have one last look at the amazing visibility
and climb out. Woo! That was great! But man is it cold! I can’t feel my thumbs! So I traveled all the way to Iceland to dive
in a crack in the ground to see some rocks and algae. This much is true. But I had to see for myself the spectacle
of such clear water. The water at Silfra comes out of the ground
as the purest glacial meltwater--with no plankton to reduce its clarity. For a few hundred meters it travels down the
crack between tectonic plates towards a lake, where it will mix with lakewater. For that short distance, divers have the chance
to experience something like flying, in water so clear, it’s like air.
