Australia is a stunning travel destination with many awe-inspiring natural wonders that cannot be found anywhere else on the planet. And it’s not just kangaroos. Together with 16 others, Australia literally breaks the barriers of bio-diversity and is part of an elite group of countries recognized as mega-diverse for their amazingly impressive numbers—and the variety—of the planet’s animal species. One pillar of this thriving ecosystem is the Great Barrier Reef, an impossibly long stretch on the north-eastern coast which is one of a few structures— and the only living one— that’s visible from space.

While there are many unique things to see and do in Australia, a visit to the land down under can never be complete without a glimpse of the Great Barrier Reef, the defining feature of the country’s stunning seascape. Here’s what makes it a must-see.

All About The Great Barrier Reef In Australia

It’s ironic that the world’s largest living structures are surprisingly the crowning act of some of the world’s tiniest living things. Measuring only about 2 millimeters in diameter, polyps are tiny, soft, and squishy invertebrates—that look like colorful sea anemones. The species that eventually make coral reefs have, like tortoises or turtles, bodies that are ensconced in a protective shell called a calyx. These shells are made of limestone, or technically, calcium carbonate. When the polyps die or reproduce, these limestone skeletons get separated from the polyps—and form stable layers on which young, baby polyps start out their lives.

Eventually, the slow wheels of time make the limestone layers grow in height and breadth, to the astonishing levels that we know them for. Scientists two years ago discovered a reef that was 500 meters tall. For perspective, that particular reef is taller than the 443-meter-high New York's Empire State Building or the 451-meter-high Petronas Twin Towers in Kuala Lumpur Malaysia.

Related: 10 Of The Most Unbelievable & Amazing Coral Reefs

Here’s why astronauts can see the Great Barrier Reef from space. The shallow lagoons that cover the coral reefs emit a sparkling, iridescent blue that significantly contrasts with the deep-toned blue of the surrounding ocean waters. Thousands of miles away in space, astronauts can mark out these uniquely colored regions. The reef itself is a structural mosaic of gigantic proportions. It sits on a vast area of over 340,000 square kilometers or 131, 274 square miles. For some bearing, the state of Florida is about 170,312 square kilometers. What that means is that the Sunshine State would go into the Great Barrier Reef twice. If it were a European country, it would be the eighth in size and larger than both the United Kingdom and Italy.

The Great Barrier Reef also stretches to an impressive 2,300 kilometers. One would travel from down south in Miami all the way to New York—and still be left with about 237 kilometers to cover. And while we talk about the Great Barrier Reef, this natural wonder is not a single reef. Instead, it’s a complex network—and system of about 2,900 separate reefs covered with 400 different types and species of coral. This is an area and an ecosystem that would need a lifetime to explore. It’s interesting that James Cook, who was fitly called an explorer, is the one who accidentally discovered these astounding marine systems on the east coast of Australia—six years before the signing of the American Declaration of Independence.

Unlike fringing reefs which cover the shoreline sea-wards, barrier reefs form something like a natural barrier some meters into the ocean leaving a deep channel—or lagoons—between the ocean’s shoreline and the ocean proper. Many corals of the Great Barrier Reef appear in a stunning pinkish glow or in some striking purplish radiance. Don’t be too quick to celebrate this breathtaking color effect. Unfortunately, that’s usually a result of coral bleaching caused by changes in environmental conditions including climate change or industrial pollution.

Related: 20 Facts Surrounding Coral Castle In Florida That Prove It's Way More Impressive Than It Looks

The Great Barrier Reef’s Bio-diversity

The Great Barrier Reef is something like an Amazon in the sea. The complex system is home to an astounding 1,500 species of tropical fish. That’s 3 times the number of tropical fish species in the Mesoamerican reef. It’s also home to over 2, 000 species of immobile aquatic invertebrates known as sponges. That’s 40% of sponge species on the globe. There are 7 species of marine turtles on the planet. The Great Barrier Reef is home to 6 of these. Then there are also numerous species of mollusks, amphibians, and reptiles that the Great Barrier Reef sustains. With these numbers, the Great Barrier Reef is one of the most biologically diverse areas anywhere on the planet.

  • The Best Way To See The Great Barrier Reef: Cairns, Port Douglas, and Lady Musgrave are three of the best spots to see the reef preferably on a liveaboard. You can experience a 3-day trip with Pro Dive for about $1,000.

Apart from just the reef, there’s a world of water sports on some pristine beaches that’ll make for a trip of a lifetime. The Great Barrier Reef deserves the name “Great.” A trip here should be made a compulsory travel adventure.