In the middle of a wide beach are pits of roiling, tea-colored, fresh water that spills into a shallow stream running down the beach face to the ocean. The eroded bare slopes of a line of low sand dunes mark the back edge of the beach, cutting off view of woods and wetlands further inland. The jet of water rising from a pit's depths brings with it a shifting cloud of suspended sand lightening the most turbulent part of the dark pool's surface.
Dimensions Spring pools are 1-3 yards/meters across. The beach extends about 150 ft (45 m) from water's edge to the the steep dune faces, which rise 20-30 ft (6-9 m). The spring is located about 100 ft (30 m) from the shore, and its outlet stream is 2-5 yards/meters wide, with depth rarely exceeding 2 inches (5 cm). The spring pits are considerably deeper funnels, with at least a foot (0.3 m) of fairly sand-free water above a narrow column of shifting, churning quicksand.
Most or all of the loose sand making up this beach is washed away by violent storm waves each winter. Calmer waves in late spring and summer slowly bring back the sand from submerged deposits offshore, creating the beach anew each year. The dunes, grass-covered and gently sloping except on their eroded faces, mark the limits of winter wave attack.
Below the beach sand is fractured sandstone bedrock. Fresh water from precipitation inland works its way toward the ocean through the rock, flowing most abundantly along a particular fracture line that empties into loose sand below the beach spring. Every year as the new beach forms, similar (but not identical) spring pits form at the same spot above the fracture outlet.
The deep color of the water is from the woodland soils inland where the supplying precipitation fell. It does not give a particularly strong taste to the water.
About five gallons (20 liters) of fresh water rise out of the spring each minute. The water looks quite clear in many places where it is running away in the shallow stream, but a bit of added depth of flow, for instance in the troughs between sand ripples of the stream bed, brings back some of its brown color.
The stream meanders back and forth in its path toward the ocean, splitting and rejoining around broad bars of sand laid down by the water. Repeated carving away of the low sand banks and building of new sand bars allows the stream bends and branches to shift their shapes day after day.
The slope of the beach face is high enough that even though shallow, the stream water runs along very actively, carrying with it a considerable load of bouncing sand grains picked up along the way. In the fastest part of the channel, the water surface is marked by 'standing' waves that weirdly creep slowly upstream, exaggerating the forms of sand ridges below that have new sand piling up on their upstream sides, and are being worn away by the flow on their downstream sides. Lapping and rushing sounds of water passing over these ridges makes the stream's flow rather loud, audible despite the breaking of ocean waves nearby.
The different angles of the water surface making up the standing wave forms make the stream sparkle in the sun when seen from a short distance out in the ocean, more likely to stand out when a boat or swimmer is approaching the shore.
Water dipped from the shallow stream will likely have some sand mixed in it. The most efficient place to draw water (though looking contaminated) is the dark brown part of the pool surface in a spring pit.
Nearby along the beach is another small freshwater stream, fed by several lower-flow seeps and springs. Much of the seepage emerges from a dark, continually wet slope of sandstone rubble, showing that the bedrock is closer to the beach surface there. Spring water flowing from beach sand has cut tiny canyons that will lengthen and widen over time, washing more sand into the stream's flow.
Oddly, this second stream runs parallel to the shoreline for some distance, before turning to run down the beach slope into the sea. It has been diverted sideways by a low ridge on the lower beach that is probably the remnant of a long, beach-parallel, underwater sand bar that has migrated up onto the shore, mobilized by gentle summer waves.
These springs provide a welcome water source for anyone washed up on the beach. Longboat crews might be happy to encounter them for immediate relief from a parched time on the salt water, especially because river mouths on this coast are estuaries whose brackish waters extend well inland.
A group camping on the beach might be happy to locate around such a convenient supply of fresh water. However tents, supply caches or cook fires placed near the outer bends of the shifting stream path might be inconvenienced by undercutting. Someone who enjoys the rushing sound of the stream water might place their bedroll on the low inner shore of a curve in the stream, only to wake up in the morning 'cut off' by inch-deep flowing water on all sides, resting on a small island created by a new branch and rejoining of the shifting stream channel.
The difficulty of shifting water could be increased/enhanced if your story included mysterious or dangerous liquids.
On a hot sunny day, a barefoot person could use the shallow stream for relief from burning sand of the dry beach surface.
Local creatures of all sorts might use this fresh water supply. Your characters might find or become prey here.
This would be a difficult place to cross quickly or with fragile items.
Someone stepping into a spring pit could be surprised to have a leg sink deeply. It would likely be quite hard to extract as sand settles around it, if it diverts or disperses the rising flow that had kept the sand suspended.
An object made of metal or other very dense material could be dropped into a spring pit for hiding. The dark water would completely obscure it. Something small like a coin or a ring would likely remain constantly tumbling around in the dense suspended sand cloud down deep in the pit. A larger object would divert the flow of the rising water jet, eroding the edge of the pit on one side, a change of shape that would be noticeable after a few hours or days. If a small cloud of suspended sand was present on the surface beforehand, it would immediately be displaced or no longer appear at all.
Something light and long buried might unexpectedly might rise up to bob in the roiling center of a spring pit.
The ever-reforming light cloud of sand in a dark spring pit might be a focus for divination or a spirit's visitation.
This is a good spot for a meditation on (or metaphor drawn form) the hydrologic cycle: The sea leaks water into the sky; the sky leaks water into the ground; the ground leaks water into the sea.
Eastern section of Brackley Beach, PEI National Park, Prince Edward Island, eastern Canada. Elsewhere in this coastal national park is the Blowout scene, in a similar dune-backed beach setting.