Waitomo Glowworm Caves - 39 Waitomo Caves Road, Waitomo, New Zealand
In 1887, an English surveyor and a local Maori Chief chose to explore the Caves of Waitomo. Using a small raft, they followed the stream underground and navigated the caves using candles for light. The two men suddenly saw many starlike lights shining above their heads. The light comes from thousands of glowworms on the roof of the cave giving a bioluminescent glow. A type of fungus gnat hangs from the roof on strings of sticky mucous. Later a land entrance was found which visitors use today.
Marble Caves of Chile Chico - Carr Austral Puerto, Río Tranquilo, Chile
The Marble Caves were formed by more than 6,000 years of waves crashing up against the calcium carbonate, forming the smooth, swirling cavern walls, which reflect the blue of the water. The colour and hue of the marble changes depending on the water levels and the time of year. The caves are only accessible by boat and thirty-minute tours are offered by a local company between September and February when the ice on the lake melts.
Mendenhall Ice Caves - 8150 Mendenhall Loop Rd, Juneau, Alaska, USA
Lying in the Mendenhall Valley is the Mendenhall Glacier, which is 12 miles in length, and 12 miles from Juneau in Alaska. Inside the glacier there are amazing blue ice caves, which involve kayaking to the edge of the ice and climbing over the glacier to access them. You would need to visit fairly soon, as due to climate change the glacier is receding. A visit to the caves has been called “surreal” and “otherworldly,” with its amazing blue glow.
Skocjan Caves - Matavun, Slovenia
These caves are referred to as being the “Underground Grand Canyon,” as it is among the largest subterranean chambers in the world. The largest cave is “Martel’s Chamber,” formed by the underground flow of the Reka River. The limestone caves were a home to humans for as far back as 10,000 years ago. It is now home to a number of species of bat, unique bio-organisms and fish that have never seen the light of day.
Sea Lion Caves - 91560 Highway 101, Florence, Oregon, USA
Located on the Pacific coast in Oregon, USA, the Sea Lion Caves are a connected series of caverns where the threatened Steller’s sea lions return each spring and summer to breed. It is the only known mainland rookery used by the species, which are the largest eared seals. The only bigger seals are the elephant seal and walrus. There is a series of walkways taking visitors to view the Sea Lion Caves. This area also serves as nesting grounds for the Tufted Puffin and Bald Eagle.