Current River Cavern, about a mile west of Van Buren, Missouri, is unusual among Missouri caves because it was formed exclusively by the stream that still flows through it rather than chiefly by older underground processes. Opened to visitors in 1940 as Cave Spring Onyx Caverns, it lies within what is now Missouri Down Under Adventure Zoo. The public tour covers about 240 feet before a flooded passage, but a 1996 survey found 2,384 feet of passages beyond that point. The cavern is also significant for becoming the first show cave lit entirely by battery-powered, wireless LED lights, reducing algae growth, limiting harm to cave life, and avoiding intrusive wiring.