Jam Up Cave is located on the Jacks Fork River between Rymers and Blue Spring. Jam Up is a spectacular cave, but can only be reached by boat. The high entrance is about 80 feet high and 100 feet wide. Much of the cave is filled with water, and there is a small underground waterfall. There is a natural skylight that provides some light to the inside. Ceiling breakdowns have occurred in the recent past, caves are constantly changing. (Of course, caution is warranted in any cave! Cave Safety Info.) PLEASE do not enter the cave,all wild caves in the park are currently closed to help control the spread of White Nose Syndrome, a disease killing bats in unprecedented numbers.
Jam Up Cave is located within the Jacks Fork Natural Area (external link). Missouri's "Natural Areas" program recognizes areas of great natural beauty or importance. This three mile stretch of the Jacks Fork River is home to four species of crayfish that are found only in the Ozarks and nine species of fish that are also limited to the Ozarks. There are many rare plants on the bluffs, some of which are "left-overs" from the ice ages. When the climate warmed, they survived in the cool wet niches among the bluffs and caves while their species became extinct elsewhere in Missouri. (Collecting any plants is prohibited by the National Park Service to preserve such rarities for your enjoyment.)