For the truly adventurous you can enjoy snorkeling through a 100,000-year-old cave that has an underground river with crystal clear waters. You also see stalagmites rising up from the cave floor, while icicle-like stalactites cling to the cave ceiling overhead.
At the Smallin Civial War Cave you can spot eerie mushroom formation made from calcium carbonate, see cave crayfish and salamanders as your trail off in 54 degree waters over a rim stone dam.
The Punta Sal National Park is home to the highest density of endangered elkhorn coral in the Caribbean as well as deep volcanic rock formations in these underwater caves. You can swim through by following the ocean currents where you might spot hammerhead sharks.
PARK CITY, UTAH
At Homestead Crater you can head to this the 95-degree hot spring and enjoy the beauty and warmth up inside.
Linwu Caves consists of four interconnected limestone caverns with springs, a stone moat and bridges. The caves are typically 68 degrees year round and have been known to have found Taoist relics inside.
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Cuevas de Mármol (Marble Caves) were formed some 6,000 years ago and can only be reached by boat. Inside you will find that the water looks blue, white and yellow in summer but can change hues throughout the year.
At the Pembrokeshire shoreline in Wales, you can scale cliffs and rocks and there is an area where you also swim and kayak into the sea caves.
In the Kan’Ba Caves you can take a lit candle in and see a a series of limestone bridges, turquoise pools fed by the waters of the Cabahón River and spot the waterfalls.
Between Albufeira Marina and Carvoeiro you will come across caves large enough to accommodate a boat where you can learn interesting facts about the location and history. You can also spot some dolphins on this excursion.
At the Lava River Cave you can enter by walking where you see up close that it was formed from molten rock that erupted from a volcanic vent years ago. This cave is pitch black so you would want to come prepared with sources of light to explore.