For some of the caves listed below, you’ll need some pretty gnarly climbing/spelunking equipment and a support crew.

For others, all you’ll need is a pair of sneakers and a few dollars.

In any case, after checking out these pics you may want to read up on how to become a good caver.

Blue Grotto – Capri

Photo: Gimas/Shutterstock

The entrance to the Blue Cave is so close to sea level that visitors usually drive up in a motorboat, then change to a small rowboat and lie flat on their backs as they pass under the rock entryway and into the cave. Inside, a second underwater entrance – which is 10 times bigger than the surface level entrance – provides light that makes the cavern appear bright blue.

Majlis al Jinn – Oman

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This is the ninth largest cave chamber in the world; locals know it as Khoshilat Maqandeli. It was discovered by Americans W. Don Davison, Jr. and his wife, Cheryl S. Jones in 1983. Cheryl’s Drop is one entrance where you can repel 158.2′ into the chamber.

Minnehaha Falls – Minnesota

Photo: Douglas R. Feltman/Shutterstock

Near where the Minnehaha Creek meets the Mississippi River, a 53′ waterfall that freezes during the winter creates a temporary cave behind a wall of ice. The Falls are part of the 193-acre Minnehaha Park near Minneapolis.

Sea Lion Cave – Oregon

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Sea Lion Cave, on the Oregon coast, is a privately owned cave that contains the wintering grounds for over 200 Stellar Sea Lions. There are also spots to view whales and bald eagles.

Crystal Cave – Bermuda

Photo: Alexander Sviridov/Shutterstock

According to local legend, Crystal Cave was discovered by two boys searching for a cricket ball in the grass. Another boy, the property owner’s son, was lowered into the cave to check it out. Today the 500-meter long underground cave is Bermuda’s most famous and contains waterways as well as caverns with stalactites and stalagmites. Read this post for nine other caves to explore in Bermuda.

Tadrart Acacus desert cave – Algeria

Photo: Patrick Poendl/Shutterstock

In the Tadrat Acacus desert, between the Tadrart Acuscus Mountains near the Algerian border, are caves containing UNESCO World Heritage rock-art dating 12,000 BC to 100 AD. The rock-art in this region is in danger due to petroleum drilling.

Cueva de los Verdes – Canary Islands

Photo: Tomasz Czajkowski/Shutterstock

Greens’ Cave, in English, is technically a lava tube. It is almost 5 miles long and has a concert hall set up near its entrance. Parts of the cave are lit up for visitors.

Cenote Ik Kil – Mexico

Photo: Tiago Fialho/Shutterstock

A cenote is a cave with no roof, or a sinkhole. Cenote Ik Kil is about 200′ in diameter and 130′ deep with vines extend from the ceiling to the water. It’s a popular swimming destination for tourists. For more on cenotes, check out Juli Huang’s report from cenotes in the Mexican Riviera.

Carlsbad Caverns – New Mexico

Photo: Doug Meek/Shutterstock

Carlsbad Caverns are visited by 407,000 people every year. It’s made up of 117 caves; three are developed caves (one has an elevator) for public tours. There are also undeveloped caves designated for “adventure caving tours.”

Badami Caves – India

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The Badami Cave Temples located in Karnataka, India is an example of Indian rock-cut architecture from the 6th and 7th centuries. Four distinct caves were carved into limestone walls. The first three caves are of Vedic faith dedicated to Vishnu and Shiva and the fourth is a Jain Temple.

Mammoth Cave National Park – Kentucky

Photo: Zack Frank/Shutterstock

Mammoth Cave National Park in Kentucky was established in 1941. It is the home of the longest cave system known in the world with 390 miles of passageways. The cave is named for its size, not the extinct animal.

Batu Caves – Malaysia

Photo: Nick Fox/Shutterstock

The Batu Caves are both an important Hindu shrine and a popular Malaysian climbing site. During the Hindu festival, Thaipusam, a procession ends at Batu Caves where offerings are left for Lord Murugan to whom the shrine is dedicated. The main caves can be reached by 272 steps up the hill. For climbers, the caves offer over 160 routes and reach 150 meters. Just be wary of the monkeys!

Blue Caves Zakynthos – Greece

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On the Greek Island of Zakynthos, the Blue Caves are cut into the cliffs around Cape Skinari and can be reached only by small boat. The white walls and pebbles of the floor reflect light giving the caves their blue hue.

Jenolan Caves – Australia

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Jenolan Caves in Australia’s Blue Mountains (~50 km west of Sydney) are the oldest discovered open system in the world, according to Australian geologists. It was also the first cave to install electric lighting in 1880. There are 40 kilometers of known passages. Though there is no public transportation to the caves, they are a big tourist attraction, bringing in 250,000 visitors every year, and the area around them is developed with hotels and restaurants. There are 10 caves that are developed for self-guided and regular daily walking tours, but much of the system is undeveloped and only explored by cavers.

Reed Flute Cave – China

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The Reed Flute Caves are over 180 million years old and has preserved ink inscriptions inside that date back to 792 BC. The cave was rediscovered by Chinese refugees fleeing Japanese troops in the 1940s and named for the reeds growing outside its entrance.

Surprise Cave – Vietnam

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On Bo Hòn Island, Surprise Cave is part of the UNESCO World Heritage site Halong Bay. The cave was discovered in 1901 and was used by the Viet Cong as a hideout during the Vietnam War. The cave is big, but so are the crowds and tour groups that come here by boats from the Bay. Want to see Vietnam’s largest cave? Check out this photo gallery.

Fingal’s Cave – Scotland

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On the uninhabited Scottish island of Staffa, Fingal’s Cave, is famous for its mysterious echoes and its hexagonally shaped basalt stone columns. It can be reached by boat; tours run from April to September.

Qumran caves – Israel

Photo: John Theodor/Shutterstock

The Qumran Cave system in the West Bank is the archeological site where the Dead Sea Scrolls were first discovered in 1947. The area is made up of real limestone caves, and artificial ones built into the cliffs. Visitors today can walk along the site and up to the caves on walking paths, some of which have views of the Dead Sea.