"This is Silfra, in Iceland, where I got to
swim between two continental plates.
"On one side of me is the North American plate.
"On the other side is the Eurasian plate.
"And here, this is where they're very slowly
tearing apart."
Every word I said there was technically true.
And I don't want this video to
take away from the magic:
swimming in Silfra was incredible,
my guides were great, I'd recommend it.
But here's the thing: this is
the Bridge Between Continents,
it's about 100km southwest of there,
and it also claims
to be the point where the two continental
plates are breaking apart.
And the two cracks, this and Silfra,
they aren't connected.
Not to each other, and not to the countless
other cracks like them across Iceland.
Now, the last time I did a video like this,
a few people got angry at me.
Because yes, I'm about to debunk something,
and if you have fond memories of diving or
snorkeling between continents,
or holding up this bridge in a photo,
this might make it a little less magical.
Particularly if you we able to
dive deep enough at Silfra
to get the photo where you touch
both sides at the same time.
"You need to be a qualified diver to head
down into the depths.
"I'm not, so I'm staying up there on the surface
with a snorkel.
"And yes, my camera lens keeps fogging up,
"I tried to do a piece to camera
while I was in the water
"but it didn't go well."
[unintelligible wet microphone noises]
Here's what true:
Silfra is a crack in the earth,
and it is between two tectonic plates.
Absolutely.
If you're diving there, you are 100% diving
in between the continents.
The bit that doesn't hold up is:
that's not The Dividing Line.
You've not got A Different Tectonic Plate
on each side of you,
you're just in the bit where they split apart.
A good way of thinking about it is:
imagine that this bridge really was between
the continental plates.
Imagine that really was the American plate,
and this really was the Eurasian plate.
What would this be, down below?
I mean, other than a lot of volcanic sand
that's getting in my shoes.
Is it neither? Both?
A bit in between?
Whatever this is, it's true for
this whole area, for kilometres.
You can see that on the map in the bridge.
This is just one of many places where the
rocks happened to be a little bit weaker,
so this is where they broke in two to let
this whole area... stretch.
Plate tectonics is messy and three-dimensional.
This is just where it looks dramatic.
As you move out of this area, east or west,
over kilometres,
the cracks become fewer and fewer,
and less and less common,
and then they stop, and then you can definitely
say you're on one of the continental plates.
But this bridge is symbolic.
Silfra is symbolic.
It's where one of the cracks happened to breach
an underground river.
But swimming in Silfra is still an
incredible experience, and here's why.
"Silfra is filled with glacial meltwater,
an underground river surfacing there,
"the water has been been filtered for decades
through rock.
"And there's so much of it that there's a
constant current
"pushing any impurities out
into the nearby lake.
"Which includes me.
"I'm swimming in a literal river of mineral
water, and the visibility is perfect.
"In other parts of Iceland, water like that
is bottled and sold.
"But here, we're inside
Þingvellir National Park,
"which was the home of the Icelandic Parliament
for eight centuries
"and is the most historic part of the entire
country.
"So, no bottling plants there.
"And because it's glacial meltwater,
"it's also only just above freezing point,
about 2-3°C,
"so I need to wear a dry suit to prevent hypothermia."
Swimming in Silfra is, technically,
swimming between the continents.
That is true.
And if there's been one theme through my videos
over the years,
it's been that the real world does not fit
into the neat little boxes that we'd like it to.
Even though we keep designing systems that
have strict categories and sharp dividing lines,
there are always exceptions.
The continents don't split at a single line.
The real world is far more messy
than we often think.
