On high ground near the centre of the Forest of Dean in west Gloucestershire, Foxes Bridge Bog is a rare example of an acid bog, a declining and now unusual habitat, traditionally home to rare plant species - marsh St John's-wort is the most uncommon plant at this location (the only occurrence in the county), while other notable examples are marsh violet and bog pimpernel. The bog occupies a minor depression and is fed by a small stream from the north, connected to Woorgreens Lake, and, like the lake and its marshy surroundings, is protected as a nature reserve, area 12 acres.
Unlike Woorgreens, which has a large parking area adjacent and is circled by well-used paths, Foxes Bridge Bog has no sign and no trails, and is rather inaccessible due to wet ground and dense vegetation. Walking is much easier across the dry oak woodland at either side, and the edges of the bog can at least be inspected. In addition to the plants, the bog is a refuge for birds and insects, these including dragonflies, damselflies and butterflies. The optimum months to visit are from May to September, when most plant species are in bloom.
The bog, originally covering a much larger area, is named after Foxes Bridge, where the road crosses the entry stream, which historically originated from marshy lands to the northeast, though the course of the stream, and other aspects of the landscape, was altered during extensive coal-mining operations in the 19th century, which included construction of a large opencast pit, now occupied by Woorgreens Lake. The bog was for a time threatened, both by the mining and proposed construction of a railway, however the surviving section has remained largely unaltered.
Foxes Bridge Bog Nature Reserve lies just south of the B4226, 2 miles southwest of Cinderford and 0.7 miles east of Speech House, a hotel occupying a 17th century building constructed for Charles II as a hunting lodge. Although not signed, the bog is recognisable for the 200 foot gap in the trees bordering the road at this point. The nearest parking place is 500 feet east, from where the edge of the bog is a quick walk through the woodland, which has little undergrowth. The main wet area is towards the north, near the road, and here are found the marsh St John's-wort plants, growing in a relatively small patch. The narrow stream flows southwards through ground that becomes gradually drier, though more tussocky and uneven so still hard to cross, up to a line of trees that once marked the edge of the forest, though the land beyond has recently been cleared, and now the open area extends another third of a mile before the woodland properly returns.