Rauðfeldsgjá is a narrow ravine cut into the southern flank of Snæfellsjökull, accessible from a small car park on the road between Arnarstapi and Búðir. The entrance to the ravine is a crack in the rock barely wide enough for one person, opening into a corridor that narrows further as you walk in. A stream flows through the bottom of the ravine; waterproof boots allow you to walk further into the increasingly dramatic cleft.
The ravine is about 100 metres deep and the walls close in overhead, reducing the sky to a thin strip of light. Mosses and ferns cover the walls where moisture collects. The experience is distinctly claustrophobic in the best sense — enclosed and separate from the open landscape outside. Most visitors walk to where the ravine becomes too narrow to continue without climbing gear, then return. The entrance path from the car park takes about 10 minutes; add 20–30 minutes for exploring inside.