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The Great Barrier
Reef has a sort of mythical quality.
What a great name! But what is it, really? And
is it all that great? Australians know all about it
but, to us, it was somewhat mysterious until we actually got
to Australia and spent some months sailing on it. And
now we live right next to it. The best place to go to
learn more is the Australian government
Web site for the
Great Barrier Marine Park Authority. I want to credit
them for many of the details and also for all the small
photos on this page. This is the one page where we
relied on someone else for photos because it is just too
difficult for us to get aerial and underwater photos and
that is the best way to appreciate it. |
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What is it?
Basically, it is a coral reef, the largest in the world.
In fact, at almost 1,500 miles long and 50-150 miles
wide, it is the largest natural feature on Earth. If
you look at the map to the left you will see it running off
the east coast of tropical Australia (inside the jagged blue
line). The reef is a
continental shelf. It used to be dry land, part of the
mainland, until ocean levels rose millions of years ago
creating a shallow shelf with some high areas still above
water. Those are now the islands of the GBR. In
the tropics, almost any underwater land within a few hundred
feet of the surface will soon be populated by tiny living
coral polyps that form all those wonderful varieties of
structures which in turn are ideal food and habitat for a
fantastic variety of sea creatures.
The shelf/GBR is very shallow - less than 100' in most
places and then drops off to thousands of feet on the
outside edge - hence, the "barrier". Ocean swells
break on the barrier part of the reef so that there is no
swell on any of the beaches inside the GBR so ... no
surfing! You still get small wind waves but all the
famous Australian surfing spots are south of the GBR.
Not every square foot is covered in coral. Some is
mud or sand-covered bottom. There are hundreds of
islands large enough to explore on foot plus hundreds of
coral islands which are too rough to walk on. The
photos below will give you a better idea. |
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Outer Reef - This is what
the GBR looks like at its outer edge where it drops off into
thousands of feet of water (deep ocean is to the right). As you can see, it is not
a solid wall. There are channels here and there where
boats can enter from the deep ocean and make their way to
ports - if you navigate carefully! But it is usually
at least 50 miles from the outer reef to the mainland so it
can be a nerve-wracking experience to weave your way through
with danger all around you. |
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Reef Island - Between the outer
reef and the mainland there are many coral islands like this
one. The whitest areas are where the coral reaches the
surface or very near. Light blue water indicates
shallow depths and dark blue is deeper. If you spend
much time in a boat around coral reefs, you learn to read
the depths. But isolated tiny reefs (sometimes called
"bommies") can be anywhere and careless boaters come to
grief by hitting them and often sinking their boats.
Coral will rip right through a fiberglass hull. |
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Reef Channels - Here you see
coral islands separated by deep channels. Really, the
best way to see the GBR is by air. These reefs are
just so incredibly beautiful from the air. Ok, they
are also incredibly beautiful as you go through them on a
boat or dive in the coral, but there are areas where these
kinds of channels and reefs form the most amazing panorama. |
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Underwater in the Coral - Healthy
coral is very colorful and teems with colorful fish.
But coral in the GBR is deteriorating in many areas.
The biggest problem has been the run-off from the rivers
which empty on to the continental shelf. Australia has
cleared a lot of land for agriculture and homes, which
increases erosion. More silt runs off into the rivers
and on to the GBR, reducing visibility and covering some
areas in silt which kills the coral. Fishing
practices have been improved but have also caused problems.
The government has recently passed new laws, but now global
warming threatens to make it too hot for the coral to
survive. |
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Large Islands of the Reef - The
larger islands were small mountains before the continental
shelf was flooded. Coral grew all around them and on
their underwater slopes. Some have fabulous resorts
(with prices to match). But if you sail up the coast,
as we did, inside the GBR, you can pull up and anchor at any
of these islands. The island in the background is
Lizard Island. You might find 50-100 boats anchored
around here in the peak season, all enjoying the
snorkeling, diving, and hiking without paying $500 a night
at the resort. The largest island inside the GBR is
Hinchinbrook, which we see from our condo. |
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Small Vegetated Islands - There
are hundreds of small islands on the GBR, mostly sand
islands. Some trees and other tropical plants can grow
in this sandy soil. We have many islands of this type
just off Cardwell. I can see them from my veranda
every day. One of the most popular local activities is
exploring these islands. Some are refuges for birds,
so you can't go ashore. No problem. You can
still anchor and go snorkelling or diving - or just gaze at
them as you sip your cold drink, bobbing in the waves.
On most islands, though, you are allowed to go ashore and
enjoy the perfect beaches or explore inland. Many even
allow camping. Most of the time, you are likely to
have your own perfect island all to yourself. Only in
the main tourist areas will you see a lot of people.
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