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What's big and blue and thought to be a portal to the center of Earth? The Great Blue Hole of Belize, of course. A little over 40 miles from the mainland, this giant gaping hole in the ocean has been catching the eye of travelers, scientists and oceanographers around the world. Let's take a closer look at this incredible natural phenomenon.

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The Basics

The Great Blue Hole is quiet, mysterious, and for the most part, largely unexplained. About 980 feet across and 400 feet deep, calling it a giant underwater cave would be an understatement. It's actually a large sinkhole that formed over 150,000 years ago and has been evolving ever since. Once a giant crater above sea level, as the ocean rose, the hole filled with water and quickly became the giant blue abyss we see today. French filmmaker and explorer, Jaques Cousteau, declared it one of the best scuba diving sites in the world. The Discovery Channel listed it as one of the 10 most amazing places on Earth. Today, it is a very popular UNESCO World Heritage Site, drawing visitors from around the world.

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What's the Big Deal?

There are other underwater caves and sinkholes around the world, but the Great Blue Hole is the only one big enough to be seen from space. The Hole also operates as it's own little microcosm with over 400 plant, animal and bacteria species unique to region. Although it seems like one giant abyss, it's actually a system of over 10 caves (that you can't see from the surface), so there's plenty for scuba divers to explore. But be careful, because the deeper you go, the less oxygen there is. The bottom is said to be pitch black and basically lifeless. Part of the Lighthouse Reef System, a number of dive companies like Ambergris Divers can take you to explore the natural wonder.

How to Do It

The Great Blue Hole is a huge attraction for the country of Belize, so you'll have no problem finding a way to get to it. Because of it's striking appearance from above, helicopter and airplane tours have become increasingly popular. Helicopter flights tend to be a bit pricier simply because you get to spend more time suspended above the Hole. Astrum Helicopters offers really great rates and a whole helicopter ride dedicated to The Great Blue Hole. For a quicker (and slightly cheaper) trip, book a roundtrip charter flight with Tropic Air from San Pedro to the Blue Hole. Both options will offer you priceless views of The Great Blue Hole and the luminous blue water that surrounds it. If diving or snorkeling is your thing, check out Seahorse Dive Shop, they offer guided diving and snorkeling tours for everyone, regardless of experience level.

Other Interesting Holes

Many tropical paradises have the pleasure of claiming their own blue hole, so if Belize is too far of a trek, chances are, there's a blue hole somewhere in your neck of the woods just waiting to be explored. Dean's Blue Hole off the coast of the Bahamas is the deepest blue hole with an entrance below sea-level, which is why it's contrast appears less defined. Other famous blue holes can be found off the coasts of Egypt, Guam and Australia, so if you ever want to feel like you're floating toward the center of the world, seek out the nearest blue hole and start diving.