Everywhere we look there seems to be an endless amount of beautiful, natural phenomena above ground like waterfalls, canyons, rivers, and mountains. However, for people who like to dig a little (or a lot!) beyond the surface, there is a whole other world of stunning natural attractions that are hidden deep inside caves all over the world.

Underground lakes and rivers usually remain hidden because of the fact that they are often located in caves which may be all but invisible to anyone who is not looking for them. Even when people are aware of the existence of large bodies of water deep underground, getting to them may be a challenge for anyone who is not an experienced scuba diver.

Thankfully, there are several caves that are not too inaccessible however. There are a number of places across the globe have created a popular tourism attraction by offering visitors an up close and personal view of the hidden gems that lie underneath the surface by providing scuba diving, boat tours, and when possible, walking tours in the caves and around the rivers and lakes hidden deep inside.

Below, we take a look at some of the most stunning underground lakes and rivers around the world discovered by brave explorers.

25 Santa Fe River

The Devil’s Spring System in Florida, United States is home to three separate springs that produce nearly 80 million gallons of water daily: Devil’s Eye, Devil’s Ear, and Little Devil. The Santa Fe River winds its way through these caves and offers spectacular scuba diving opportunities. The water is so clear that the guided tours boast that one could go all the way to the bottom of the 20-50 foot deep water-filled caverns and look up to see the trees and sunlight overhead clearly. Depending on the level of expertise, divers can choose how deep they want to dive and explore the wonders of rarely seen underground caves. (ginniespringsoutdoors)

24 Abismo Anhumas

In order to visit the lake inside of Abismo Anhumas in Brazil, visitors must first complete a mandatory drill the day before to ensure safety as they rappel down 72 meters to land inside the cave and the 80 meters deep blue/green lake that awaits. There are various incredible stalactite and stalagmites formations that are illuminated in some parts by the rays of sunshine that manage to make their way down so far underground, and for those who have experience, they can also explore the crystal clear waters further by taking diving expeditions up to 18 meters deep. (visitbrasil)

23 Lake Martel

Located in the island of Majorca near Spain, Lake Martel lies 25 meters underground in the Cuevas del Drach, “The Caves of Drach,” which are part of a series of four great caves. The Lake measures approximately 115 meters in length and 30 meters in width. Discovered in the 1880s, the caves have become a very popular tourist attraction and various ways of exploring the caves are possible, including a guided boat tour that ends in a live classical concert! In addition the Lake Martel, there is also another, smaller lake and the “Baths of Diana” which are filled with turquoise water. (cuevasdeldrach)

22 Seegrotte

Located underneath a former gypsum mine in Hinterbrühl, Austria, Seegrotte tells the story of an accident that ended up working out quite well. Seegrotte is a series of underground canals that make up Europe’s largest subterranean lake; but this was not a natural occurrence. A detonation gone awry in 1912 flooded the lower gallery of the caves 60 meters underground and water now covers approximately 6,200 square meters. The caves have been open to tourists since 1930 and visitors can take a boat tour to enjoy the beauty of the lake and learn from the small displays set up along the way that tell the story of a human miscalculation turned natural wonder. (atlasobscura)

21 Grjótagjá

Located underneath north Iceland, Grjótagjá lava caves sit near Lake Mývatn and are home to some very unpredictable hot springs. Prior to the 1970s, people around the area used to enjoy the hot springs located within the caves as a relaxing treat. Unfortunately, the proximity of the caves to the Krafla volcanic system, the country’s most explosive volcanoes, caused the water’s caves to boil and release toxic gases which made it dangerous for public use until this day. Despite it being over 3 decades since the last volcanic explosion, liquid rock lies beneath the surface of the earth which makes the heat of the water shift very unpredictably. (guidetoiceland)

20 Río Secreto

Río Secreto means “secret river” in Spanish and is a system of underground caves, rivers, and cenotes located in the Yucatan Peninsula in Mexico. The awe-inspiring stalactites, stalagmites, helictites, and columns make it seem like a completely different world underground and it is a very popular attraction in the area. Río Secreto consists of more than 7.5 miles of semi-submerged river caves that contain cool, clear water which perfectly reflect the beautiful natural beauty on the cave walls and ceilings. The best thing about this beautiful river is that it is easily accessible and visitors can walk or wade through most of it. (haciendatresrios)

19 Reed Flute Cave

Located in Guilin, Guangxi, China, the Reed Flute Caves have also been called “The Palace of Natural Arts” and almost gives the impression that we are in another world. The name Reed Flute Cave came about because the type of reeds growing outside of the cave can be made into flutes. In addition to the natural wonders of stalactites and stalagmites and various small lakes, multicolored artificial lighting provides an otherworldly experience for visitors. The cave has quite an interesting history as well; discovered by refugees in 1940s and now open to the public, there have been inscriptions on the cave walls that date back to over 1,000 years ago. (atlasobscura)

18 St Léonard Lake

Measuring in at a length of 300 meters, 20 meters wide, and 10 meters deep, Saint-Léonard underground lake is located in Valais, Switzerland in the middle of the Swiss Alps and is also widely considered to be one of the largest navigable underground lake in Europe. Accessible to tourists since 1949, there are many guided boat tours in various languages that take visitors throughout the cave and lake to learn more about its formation, history, and to witness some of the trout that swim freely in the crystal clear water. Because the cave is inaccessible by foot and no swimming or diving are allowed, boat tours are the only way to explore the area. (myswitzerland)

17 Melissani Lake

On the small Kefalonia Island in Greece, Melissani Lake invites visitors to explore the beauty of light as the sun enters through the opening of the caves to cause the water below to sparkle in an almost magical display of natural beauty. The area is surrounded by lush forests and inside the cave lay two chambers, one of which is dotted with vegetation and lit by the sun which causes the cave walls to look like they are sparkling. The other chamber lies in darkness, covered in algae and moss and might inspire a more somber reflection beneath the Earth’s surface. (kefaloniaisland)

16 Lost River Cave

Lost River is part of the Lost River Cave system which is a seven mile cave in Kentucky. The river itself is only 400 feet long, but appears above ground in three small sections before flowing into the mouth of the cave. One of the distinguishing features of the Lost River is the fact that it runs through a cave that was once believed to be inhabited by tribes native to the area. Archaeologists have found spear points used for hunting game and hypothesize that the location was ideal since it provided ample shelter and a fresh source of water. (lostrivercave)

15 Sistema Sac Actun

Sistema Sac Actun is a part of the longest documented underwater cave system in the world. It is located on the Caribbean coast of the Yucatan Peninsula and measures over 140 miles long. The entire Sistema Sac Actun is located under the state of Quintana Roo in Mexico and is the longest cave in Mexico, and the second longest in the entire world. One of the most fascinating features of the cave is the remains of a mastodon and a human, teenage female found at 187 feet and 141 feet respectively underneath the ground, making it the oldest evidence of humans in the area. (sites.northwestern)

14 Lago Azul

Located in Brazil, Lago Azul, also called Blue Lake Cave, is about 80 meters deep and one of the largest flooded cavities on the planet, unknown to the world until its discovery in the 1920s. The lake is widely known for its intense blue color when the sunlight shines through a hole in the ceiling. Underneath the lake, there is a lot of history to discover because the fossils of prehistoric animals such as the giant sloths and saber-toothed tiger have been found. Because of these incredible finds, Lago Azul is listed as a natural monument and preservation area due to its beauty and fragility. (atlasobsucra)

13 Hang Sơn Đoòng

Believed to be between 2 and 5 million years old, Hang Sơn Đoòng Cave is located near the Laos-Vietnam border and the largest known cave passage in the world in terms of volume. The cave passage measures over 3 miles long, 660 feet high, and 490 feet wide. The cave itself runs for over 5 miles and in several areas where the cave has collapsed, life has pushed through and trees and other vegetation have taken root and flourished deep underground. Hang Sơn Đoòng means “cave of the mountain river” and its discovery was relatively recent in the early 1990s, with tours starting as recently as 2013. (oxalis)

12 Xe Bang Fai River

The Xe Bang Fai River is located in the incredible Tham Khoun Xe Cave deep in Laos that are not for the faint of heart. In addition to the usual stalagmites in the Tham Khoun Xe caves, there are also numerous giant spiders that make the dark caves where the river is located their home. Tham Khoun Xe Cave measures around 76 meters in width and 56 meters in height and is home to one of the largest known river passages in the world. Visitors can walk through the caves (if they don’t mind the possibility of encountering larger than average spiders!) which is almost 4.5 miles long. (smithsonianmag)

11 Pivka River

Running underground through the highly popular Postojna Caves, the Pivka River is located in Slovenia and runs 17 miles in length before it merges with the Rak River and the Unica River in Planina Cave, known as one of the longest Slovenian water caves. The Pivka River created the Postojna Caves which offer numerous guided tours and a first in cave exploring: a double decker train ride through the caves! Visitors have the option of a variety of different tour times and difficult levels and the Pivka River is only one of the many other natural attractions people get to enjoy. (postojnska-jama)

10 Wimsener Höhle

The Wimsener Höhle, also known as Wimsen Cave, is Germany’s only water cave. Although the cave itself is over 720 meters in length, only about 70 meters are accessible to visitors on boats. After the first 70 meters, visitors will have to brave the darkness and wetness to explore further since the ceiling drops down to the water surface and is only accessible by diving. The cave is estimated to be about a million years old and was not fully explored until the 1950s when divers were able to find a small hole underneath the water and continue the exploration. (tripadvisor)

9 Dragon's Breath Cave

Named because of the hot humid air that rises from its surface, Dragon’s Breath Cave in Namibia near the Kalahari Desert is a recent discovery, but an important one. Details about the cave and lake were unknown until 1986 and as of today, no one knows exactly how deep down the water extends. Divers have only been able to go as far down as 430 feet which makes it the largest underground non-subglacial lake in the world. Because it is shielded from the elements above, the water is crystal clear and relatively motionless which allows people to see far down into the depths. (lakescientist)

8 The Lost Sea

The Lost Sea is located deep inside a mountain in East Tennessee and is listed by the Guinness Book of World Records as America’s largest underground lake, despite the remarkable fact that recent teams of explorers with modern equipment still have not been able to accurately document the full extent of the Lost Sea. From what we can see however, the lake measures 800 feet long and 220 feet wide and is home to some of the largest Rainbow trout in North America. The Lost Sea resides in the famous Craighead Caverns where various artifacts from the Cherokee Indians once living in the area have been found. (thelostsea)

7 Dream Lake

Located in the well-known Luray Caverns in Virginia, United States, Dream Lake is like a floor mirror that reflects the beautiful multihued stalactites, stalagmites, and columns formed from millions of years of flowing underground rivers and erosion. Although Dream Lake is only about 18-20 inches at its deepest point, the lake is a perfect reflection of the abundance of stalactites hanging from the ceiling. It is most known for being the site of the world’s largest musical instrument, visitors can tap the Great Stalacpipe Organ with provided strikers and create sounds that produce similar sounds to xylophones or tuning forks. (britannica)

6 Puerto Princesa Subterranean River

The Puerto-Princesa Subterranean River is a part of the larger Puerto-Princesa Subterranean River National Park system which is known for being a biodiversity conservation and it contains some of the most important forests in Asia. The River and National Park are located in the south-western part of the Philippine Archipelago and the underground river measures to over 5 miles long. One of the distinguishing characteristics of the Puerto-Princesa Subterranean River is that it flows directly into the sea which means that the lower half of the river is subject to tidal influences, a natural phenomenon that is rare. (whc.unesco)