The cave’s named for an underground lake — really more like a large pool — of clear, cool water. Our tour took about 40 minutes. The year-round air temperature is 52 degrees. Bring a jacket.

You could add that to your coming-year bucket list, if you're up for joining a tour of the Crystal Ice Cave at Lava Beds National Monument.

Crystal Cave in Sequoia National Park, California, reopens for the season, offering guided tours and a magical underground experience after a 4-year closure.

People over the age of 12 can tour Crystal Cave for $20, while ages 4 to 11 can enter for $15. Mini golf and gemstone panning cost an additional $6 and $8, respectively.

Clear pure water flows in the cave. Insiders look at Lost River Caverns in Hellertown on Tuesday, Oct. 31, 2017. The limestone caverns consists of 5 chambers. Discovered in 1883 the cavern was ...

One of the most interesting caves in Utah is Crystal Ball Cave, located in Gandy, Utah, and is one of Utah's most underrated gems. Discovered in 1956 by George Simms while searching for a lost ...

Crystal Cave in Sequoia National Park, California, reopens for the season, offering guided tours and a magical underground experience after a 4-year closure.

Crystal Cave in Sequoia National Park, California, reopens for the season, offering guided tours and a magical underground experience after a 4-year closure.

After a four-year closure due to natural disasters, Crystal Cave in Sequoia National Park reopened to the public in time for Memorial Day, the unofficial start of the summer.

The water, typically cool and crystal clear, contained some sediment due to recent storms. “It’s purified and safe to drink,” said Koppus, although it doesn’t taste too good.

Along the way, they met Bob Carr, the creator of Bob's Crystal Cave near Joshua Tree, Calif., where he welcomed visitors for 15 years. Bob died earlier this month at age 80.