36 CFR § 7.68 - Russell Cave National Monument.
(a) Caves—(1) Closed Areas. Entering, exploring, or remaining within any cave area other than the public archeological exhibit without prior written permission of the Superintendent is prohibited.
(2) Permits. Permits for entry into other than public exhibit areas of the cave will be issued within limitations of safety provided the applicant satisfies the Superintendent that he has proper equipment for cave exploration, such as lighting equipment, protective headwear, and appropriate shoes or boots. Other reasonable administrative requirements may be imposed by the Superintendent provided reasonable notice of these requirements is given to the applicant.
(3) Solo Exploration. Solo exploration is not permitted in the caves other than in the public archeological exhibit areas.