Den Våde Ovn Sea Cave, Hammershus

A hidden sea cave beneath Hammershus

Den Våde Ovn is a long, narrow sea cave sliced into the steep granite coastline between Allinge and the ruined fortress of Hammershus on Bornholm’s wild northwest corner. From the clifftops above, you might never guess that a 70 m deep corridor has been hollowed out by centuries of wave action, but from the water the entrance appears as a dark vertical slit in the rock, framed by sheer walls and lichen-streaked stone. The cave’s name, literally “the Wet Oven,” hints at its shape: like a rocky oven or chimney filled with surging Baltic water. Swells roll in and out of this confined space, amplifying the sound of the sea and sending spray up the walls. It is a striking natural counterpoint to nearby Hammershus, whose medieval ruins watch over the same stretch of coast from high above.

Bornholm’s granite coast shaped by the Baltic

This part of Bornholm is famous for its dramatic granite, and Den Våde Ovn is one of the clearest demonstrations of what wind, waves and winter ice can do to hard rock. Vertical fractures in the granite gave the sea a starting point, and over thousands of years the cave was slowly enlarged as storms forced water, pebbles and sand into the crack. Around the cave, the coastline is a gallery of sculpted formations with names like Løvehovedet (the Lion’s Head) and Kamelerne (the Camels). Jagged headlands, boulder-strewn shores and sheer cliffs provide nesting ledges for seabirds and striking views in every direction. Seen from a small wooden boat at water level, the scale of the cliffs and the depth of the cave feel particularly impressive.

Experiencing the cave from the water

There is no path or platform leading into Den Våde Ovn; the only way in is by boat. Traditional wooden sightseeing boats depart from Hammerhavn and follow the cliff line, edging as far into the cave as sea conditions and safety allow. On calm days you may glide deep into the shadowed interior; when swells are larger, the boat typically pauses near the entrance so passengers can still appreciate the echoing acoustics and sense of enclosure. Inside, the temperature often drops noticeably and the light changes from open-sky brightness to a muted, greenish glow reflected off the water. You can watch reflections dance on the rock walls and hear the slap of waves amplified by the stone corridor. Even without stepping ashore, the short passage into the cave feels like entering another world, hidden just behind the sunlit cliffs.

Wildlife, seasons and changing moods

Den Våde Ovn and the surrounding coast support a variety of birdlife, especially during the warmer months when ledges above the waterline are busy with nesting and resting seabirds. The cliffs are streaked with hardy vegetation that clings to cracks in the rock, and in summer the contrast between bright green growth and grey granite is particularly striking. Conditions on the water change quickly with the season. In calm summer weather the approach to the cave feels tranquil, even meditative, while in windier periods the same landscape takes on a more dramatic, elemental character as waves boom into the confined space. Boat operators adjust how far they enter the cave depending on swell and visibility, so each visit can feel a little different.

Planning a visit along the Hammeren coast

Most visitors combine a boat excursion to Den Våde Ovn with time exploring the wider Hammeren and Hammershus area. From the sea you gain a low, close-up perspective on the cliffs, while trails on the heights above offer sweeping views over the Baltic and the route the boats take. The experience does not require special equipment beyond weather-appropriate clothing; the boats provide seating and a relatively gentle pace along the shore. Because access to the cave is entirely dependent on boat operations and sea conditions, it is worth allowing some flexibility in your plans. Mornings and evenings can feel especially atmospheric on the water, with softer light on the rock faces, while midday trips emphasise the stark colours and sharp contrasts of granite, sea and sky. Whichever timing you choose, the combination of Hammershus, Hammerhavn and this concealed sea cave makes for a distinctly Bornholm coastal experience.