Great Barrier Reef

Seeing the entire Great Barrier Reef could take weeks, but the most important scuba diving and snorkeling spots include the Saxon, Hastings, and Norman reefs in the outer Great Barrier Reef. Join one of the area's many snorkeling and scuba dive–centric cruises or day trips, or turn your trip into an educational opportunity by getting your PADI (Professional Association of Diving Instructors) certificate.

Alternatively, explore this UNESCO World Heritage Site from above with a cruise in a catamaran or a glass-bottom boat. Scenic helicopter flights offer an overview and will give you a sense of the immensity of this remarkable ecosystem.

• The Great Barrier Reef is one of Australia's most iconic and must-see attractions for all visitors.

• Keep in mind that strenuous water activities are not recommended for people with medical conditions affecting the heart or lungs.

• If you experience motion sickness, take preventative medication at least 30 minutes prior to boarding the boat.

• A stinger suit to protect you from jellyfish is recommended for swimming in the waters off Green Island and Fitzroy Island, or the Frankland Islands.

The Great Barrier Reef runs 1,426 miles (2,300 kilometers) from Bundaberg to Australia's northernmost tip, coming closest to the continent right around Queensland. Scuba diving excursions, snorkeling trips, and reef cruises depart from Cairns, Cape Tribulation, Port Douglas, and Townsville. The trip to the Great Barrier Reef from Cairns can take 45–90 minutes, depending on where you're headed.

The water is at its clearest from April to October, but the reef can be enjoyed all year round. From December to March (summertime in the Southern Hemisphere), the water temperature is around 86℉ (30℃). From May to August whales migrate to the reef, and in the spring the coral spawns.

A popular way to experience the Great Barrier Reef, Reefworld Pontoon consists of two giant pontoons floating over Hardy Reef, part of the Great Barrier Reef. Here, you can snorkel and dive, explore in semi-submersibles, or stay dry in an underwater viewing chamber. Tours to Reefworld depart from Port of Airlie, near Airlie Beach on the coast of Queensland.

Whether you join a boat cruise around the islands and cays, enjoy aerial views on a seaplane or helicopter flight, or take a glass-bottom boat tour, the Great Barrier Reef is a head-turner. The one thing you can't miss? Snorkeling or scuba diving amid kaleidoscopic coral gardens and rare marine life.

Queensland's balmy tropical heat means you can visit the world's largest reef all year round, but the best time for snorkeling and scuba diving is during the dry season (May through October). With minimum rainfall, maximum underwater visibility, and lower humidity, June is one of the best months to visit.

Dazzling bands of coral reefs, hundreds of sandy islands and cays, and pockets of lush rainforest—a tour of the Great Barrier Reef is simply unforgettable. Along with 2,900 coral reefs and 1,500 fish species, you can spot turtles, manta rays, whales, and rare and endangered marine life.

Yes. It's a smart idea to book your Great Barrier Reef tickets for a tour in advance, especially during peak season (June–July) or if you have a specific tour or activity in mind. But don't worry if you haven't booked—finding a day tour at the last minute is often still possible.

Look but don't touch is the main rule at the Great Barrier Reef. Take care not to touch or kick the coral, refrain from feeding fish and other marine life, don't take any natural "souvenirs," and wear reef-safe sunscreen to help preserve fragile natural ecosystems.

June and July are the most popular months for snorkeling tours of the Great Barrier Reef, and for good reason. Low rainfall and cooler temperatures mean underwater visibility is at its highest, making this the perfect time to admire the vivid coral formations and spot rare marine life.