Eureka Dunes are the tallest in California. NPS - Dan Kish. A pale mountain of sand appears to hover over the flat valley floor. Rugged cliffs loom high above, boldly striped with pink, gray, and black. The distant yipping of a coyote is interrupted by a mysterious rumbling sound emitting from the dune itself. Welcome to Eureka Dunes, one of the newest additions to Death Valley National Park.