Son Doong among top wonderful caves in the world

Son Doong is 200 meters wide, 150 meters high, and about 9 kilometers long. The beauty of this cave is enhanced by its vegetation, derived from the collapse of a roof in one of the caverns. The surreal landscapes convinced the BBC news that Hang Son Doong is one of the most fascinating caves in the world. And the pictures speak for themselves. The entrance in Hang Son Doong cave is 10 kilometres (forest path) away from Truong Son Highway, and the nearest city is Dong Hoi (65 kilometres away).

The Mendenhall is a glacier measuring more than a half mile wide in its widest point, and about 540 meters in its deepest. Mendenhall Glacier has a total length of 12 miles, extending between Juneau Icefield and Mendenhall Lake. Commercial operators offer tours in the summer, including hiking, biking, rafting, canoe and kayak trips, and bus, van, taxi and shuttle tours. Given the fact that the glacier`s melting process is severe, it is strongly recommended that visitors do not enter the caves during summer and they should wear proper equipment.

The Blue Grotto, or Grotto Azzurra, is one of the top attractions in Capri, Italy. The stunning blue water of the cave was a favorite swimming destination of Roman emperor Tiberius, who decorated it with statues of the gods Poseidon and Triton.

Waitomo region is part of the North Island of New Zealand, and it is exclusively known for its population of glowworms. They are known as Arachnocampa luminosa and their habitat is very well preserved (since they only exist in New Zealand) by a special Scientific Advisory Group. Using high-tech tools, they determine the management of the cave environment by checking the air quality, temperature, humidity and carbon dioxide. And yes, that means that they decide how many people enter the caves every day.

It's also home to thousands of birds, who spiral out of the cave's mouth each day at sunrise, a sight that is popular with tourists. The cave is also a hot spot for adventure-seekers, who base jump or rappel down the cave's walls. 

The cave is placed on the uninhabitated island named Staffa, property of the National Trust for Scotland and is 72 feet tall and 270 feet deep. The cave is also known as  An Uamh Binn, or The Cave of Melody, due to the harmonious sounds that you hear after you get closer.

Algar de Benagil is one of the most widespread locals when the subject is the Algarve beaches, including the international press. No surprises, this beach / cave is incredibly beautiful. This place is actually a grotto, that means it is a natural cavity. This specifically is called grotto, or algar in portuguese, of Benagil and it is located close to the Benagil Beach. For those who live or will spend several days in Algarve, may be worth contacting the company you choose for the tour and ask how the sea appears to be. This because in some days the sea is quite transparent, and others not so much. This variant can make your tour even more beautiful.

The spectacular Giant Crystal Cave is connected to the Naica Mine, located in Chihuahua, Mexico, 300 meters bellow the surface.  Its main chamber contains the largest selenite crystals ever found, some of them reaching 11 meters in length, 4 meters in diameter and about 55 tons in weight. Source: Business Insider