In this chapter, we review the major extracellular fluid compartments in the eye and inner ear of humans. We begin with the extracellular fluids that characterize the ocular system: the aqueous humor in the anterior cavity of the eye, the vitreous humor in the vitreous chamber, and cerebrospinal fluid in the optic nerve sheath. Intraocular pressure is defined, and Goldmann’s equation for intraocular pressure is discussed. Briefly, we also touch on two topics of current interest: the lymphatic system and the newly proposed glymphatic system in the human eye. Next, we turn to the fluid compartments of the inner ear, starting with a basic introduction to human ear anatomy. Two extracellular fluid systems—endolymph and perilymph—are introduced, as these compartments are integral to the inner ear’s fluid physiology. Anatomical and functional communications between these fluid compartments are examined. After describing hearing function under physiological conditions, we discuss Meniere’s disease, a well-known inner ear disorder. Relevant to Meniere’s disease are the classical animal experiments by Friis and Qvortrup, which explore the role of disturbed venous fluid dynamics in understanding the disease. We also discuss the role of venous occlusions in inner ear pathologies. The chapter concludes with a summary and suggestions for further reading.