Black Chasm Cavern is an underground cave system that was deemed a National Natural Landmark by the National Park Service in 1976. Visitors can take tours of the main cavern via viewing platforms, stairs and walkways that allow access to the cave's rare and unusual natural formations, including stalactites, stalagmites and crystals. Aboveground, a Visitors Center doubles as a gift shop and houses movie props with information about the cave's surprising connection to the Matrix films.Parking and public transportation at Black Chasm CavernNo public transportation is available in the immediate area but parking can be found onsite, free of charge. The parking lot can sometimes fill to capacity on unusually busy days but the tours typically last about 45 minutes and escort large groups at a time, so if you run into a packed lot just take a short drive and circle back around. Odds are good that several spaces will open momentarily.Best and worst time to go to Black Chasm CavernBeing a popular location for school field trips, the tour schedule tends to get bogged down by such groups on weekday mornings during the school year (late August through early June). During those months, it's best to visit in the afternoon during the week or anytime on the weekend when the crowds can be hit-or-miss, often depending on the weather.Admission to Black Chasm CavernEntrance to the Visitors Center is free. Black Chasm was the inspiration for "Zion" in the second Matrix movie, so aside from a gift shop and information on the cave itself, you'll also find movie props from the Matrix film inside the Visitors Center. The cave itself can only be accessed via the "Walk Tour" which costs about $15 per person with discounts offered for children and seniors, but if visiting on your birthday bring your ID to get in for free.Must see/do at Black Chasm CavernObviously the cave is the biggest draw at Black Chasm and tours run throughout the day. Unfortunately when it gets especially busy, visitors have no choice but to burn time until their group is scheduled to go underground. In these cases, heading outside to the mining flumes to pan for gold and gemstones is the best option. It only costs about $7 to go "panning", which can easily keep both children and adults busy for 30 minutes to an hour (or longer). Doing so is especially enjoyable in the hot summer months, when getting your hands into the cool water is a welcome break from the hot temperatures outside while you wait to enjoy the dark cool year-round 57-degree cave.Other places to visit near Black Chasm CavernIndian Grinding Rock State Historic Park is a very short drive from Black Chasm and offers an unparalleled opportunity to explore the customs and dwellings of the native Miwok people. The 135 acre park is home to 1,185 bedrock mortar holes (the largest collection of such in North America) as well as actual petroglyphs of various shapes and animals, some thought to have been carved as long as 3,000 years ago.Insider tip for visitors to Black Chasm CavernIf visiting during March or April, take a small detour to visit McLaughlin's Daffodil Hill on your way to the Black Chasm. The same family has owned this 4 acre ranch since 1887, during which time they have continued to plant more and more daffodil bulbs every year. When the estimated 300,000 bulbs (in more than 300 named daffodil varieties) are in bloom, the McLaughlin family opens their property to onlookers free of charge. Needless to say, the sight is breathtaking.Author's bio: Ann Milligan is a wife, mom, author and artist who resides in California's beautiful Motherlode region. She can often be found painting the local wildflowers, singing off-pitch with her kids and nom-nom-noming.