Hidden Spring | Bone Cave

Location: Washington County, Florida, United States

Hidden Spring, also known as Bone Cave, is located in Holmes Creek southwest of Vernon, Florida.

The system receives its names from two distinctive characteristics: the concealed nature of the spring’s entrance and the presence of fossilized bone within the cave. The opening lies in a small, nondescript section of the creek floor and is not visible from the surface under normal conditions.

Geological Context
Structure & Layout
Hydrological Characteristics
Fossil Features
Exploration & Mapping
Cave Data
Current Status

Geological Context

The spring discharges from the Floridan Aquifer into Holmes Creek.

The creek water is frequently tannic, obscuring the spring from surface view. A subtle clearing in the water just outside the opening marks the discharge zone.

The entrance is low and requires sidemount configuration to access. Beyond the restriction, the cave opens into more moderately sized passage.

Structure & Layout

The entrance is low and requires sidemount configuration to gain access.

Immediately beyond the initial restriction, the passage opens into more navigable space. The main line continues straight for approximately 100 feet before reaching an intersection.

At this intersection:

One passage leads toward a section where the fossilized spine of a dugong is visible embedded within the limestone wall.
The primary passage continues into additional segments of the cave.

One looped section consists of a narrow, winding passage with several small offshoot tunnels. Another primary route continues several hundred feet through a low, silty area where improper technique can quickly reduce visibility.

The system contains a mixture of confined passage, loops, and sediment-sensitive sections.

Hydrological Characteristics

Hidden Spring exhibits steady but moderate discharge relative to other Holmes Creek systems.

Because the opening is small and positioned in the creek floor, entry conditions can vary depending on creek stage.

Interior flow remains manageable once beyond the initial restriction, though the silty sections require precise buoyancy control.

Fossil Features

Hidden Spring is also known as Bone Cave due to the presence of a fossilized dugong spine embedded within the limestone wall.

Dugongs, marine mammals once present in Florida’s ancient waters, no longer inhabit the region. The preserved vertebral column visible within the cave reflects the marine origins of Florida’s limestone formations.

This fossil feature is one of the defining characteristics of the system.

Exploration & Mapping

Exploration of Hidden Spring documented the primary passage and its looping branches, clarifying the internal layout and establishing mapped passage through multiple sections.

Survey work confirmed the branching configuration and identified the fossil-bearing corridor as a distinctive interior landmark.

Due to its low entrance and silty interior sections, it is generally approached by divers trained in sidemount configuration and careful propulsion techniques.

Portions of this cave system were explored and surveyed during cave dives conducted by Rob Neto while documenting Florida’s underwater cave systems for the book The Hidden Rivers of Florida.

Cave Data

Location: Washington County, Florida
Water Source: Floridan Aquifer
Cave Type: Submerged limestone cave system
Depth Range: 15–60 feet (4.5–18 meters)
Water Temperature: ~68°F (20°C)
Geology: Karst limestone
Primary Access: Spring vent
Exploration Status: Partially explored

Current Status

Hidden Spring remains a subtle and easily overlooked system within Holmes Creek. The entrance remains difficult to identify without prior knowledge of its location.

The combination of:

Low sidemount-only entry
Fossil presence
Looped narrow passage
Silt-prone interior sections

makes the system technically manageable but sensitive to diver technique.

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