TUNNEL ABSEILING PLUS tour the underground

The unusual part comes first: you enter a 550-meter World War II fortress and descend natural rock by rope before exploring its concrete underground rooms. San Giovanni was never finished, so you get an odd meeting of rough stone, man-made tunnels, and forgotten military architecture.

I like the way the tour builds confidence in stages, starting with a horizontal practice session before the real descent. I also like the small groups, limited to eight people, and the patient guidance offered by licensed instructors such as Sara and Marko. The main caution is simple: non-slip footwear is mandatory, and the cool, enclosed setting will not suit people with claustrophobia or epilepsy.

Key points to know before booking

• Three possible abseiling experiences: Start with an easier walking descent, try a more demanding vertical jump, and choose the cascading-rock descent on Abseil Plus.
• A 550-meter underground fortress: San Giovanni combines unfinished concrete construction with natural rock inside a former World War II site.
• Beginner-friendly instruction: You receive an equipment briefing, technique lesson, practice exercise, and demonstration before descending.
• Small groups of up to eight: The limited group size allows instructors to give personal support and lets the tour move at a calm pace.
• A cool 14 to 16°C underground: Bring a warmer layer even in hot Croatian weather.
• The finale mixes history and atmosphere: Expect audio-visual effects, a time-themed presentation, optional pitch-dark navigation, and wine at the end.

Entering San Giovanni fortress

This is not simply a rope activity placed in a cave. The setting does much of the work. San Giovanni is a 550-meter underground fortress from World War II, left unfinished and later forgotten before being prepared for visitors.

That unfinished state gives the place its character. You see concrete rooms made by people, then natural rock surfaces that interrupt the strict military design. The result feels less polished than a standard museum, but that is part of its appeal. You are not walking through a restored palace with tidy labels. You are moving through a rough, unusual structure where nature and construction share the same space.

The fortress has two levels, and the route includes high underground rooms built in concrete. Special effects accompany the walk, adding sound and projected images to the historical setting. I would not book this expecting a long conventional history lecture. The history comes through the place itself, the guided explanation, and the audio-visual presentation.

The underground temperature remains around 14 to 16°C. That is pleasant relief during a hot Croatian summer, but it can feel chilly once you stop moving. Pack a light jacket or warmer top rather than relying on summer clothing.

Learning the ropes before the first descent

The tour begins with an introduction to abseiling and the equipment. All required gear is supplied, and it is certified to current standards and checked regularly.

You first practice on a horizontal surface. The instructor then demonstrates the descent before you put on the equipment and approach the vertical natural rock. This order matters. If you have never used a rope system, the practice gives you a chance to understand the basic movements without also dealing with height and uneven ground.

You do not need previous abseiling experience. The instructors provide professional support and backup throughout the activity, and you can decide on the spot which descent feels right for you.

That flexibility is one of the tour’s strongest features. A person who wants an easy introduction does not have to commit to the hardest option at the start. You can gain a feel for the equipment, watch how the system works, and choose according to your comfort level.

The easier descent involves walking down a vertical rock face while supported by the rope. After that, you may repeat the descent in a slightly harder version involving a vertical jump. Both are intended for beginners, with instructors assisting and backing you up.

I like this progression because it treats nerves as normal. You are not expected to arrive already confident. You are shown the technique, given a practice run, and allowed to choose your level.

What Abseil Plus adds

The $88 Abseil Plus tour includes an additional descent beyond the first two options. After the initial rock descents, you can try a cascade of rock inside the fortress.

This section is more demanding because the rock is uneven and slippery. That makes footwear especially important. Hiking shoes or sturdy sports shoes with non-slip soles are required, not merely recommended.

The earlier descents act as preparation for this section. You develop a basic sense of how to position yourself and control the rope before reaching the more awkward rock. If you find the first descent challenging, you can keep your experience at that level. The choice is based on your comfort.

Abseil Plus also allows a simultaneous descent in pairs. That gives the activity a social element, though the setting remains the main attraction. You are working with the rope, listening to instructions, and dealing with the unusual rock surface rather than simply watching a performance.

For many people, the added descent is what makes the Plus version worth the price. You get more active time and a wider range of surfaces. If your main goal is only to see the fortress and try abseiling once, the simpler Abseil option may be enough. If you want a fuller challenge and feel steady after the first descents, Plus gives you more to do.

Walking through the concrete rooms

After the outdoor or natural-rock descent, you enter the high underground rooms. The change in setting is part of the fun. The first moments focus on technique and movement, while the fortress walk gives you time to look around and take in the scale of the structure.

The special effects add a theatrical layer to the route. You may hear or see material designed to bring the site’s past into the present. The final audio-visual surprise is intended to transport you back in time, so the tour finishes as more than a climbing exercise.

I would keep your expectations practical. The supplied information does not describe a full museum collection or a detailed room-by-room military exhibit. What you get is a guided visit through an unusual underground fortress, supported by projections and audio-visual material.

That is still valuable for a short activity. A standard abseiling session might give you the physical challenge and little else. Here, the place gives the activity a clear sense of purpose. You are not simply descending a wall at an artificial climbing center. You are using ropes inside and around a former military structure with a complicated relationship between rock and concrete.

The pitch-dark challenge

Near the end, the bravest participants can turn off their head torches and try to find the way out in complete darkness.

This is optional, which is important. You can enjoy the guided route without taking this extra step. If you do choose it, expect a short but striking test of orientation and nerve. The darkness changes the fortress from an architectural site into a sensory experience. Without the lights, even a familiar passage can feel uncertain.

This part may be memorable, but it is also where personal comfort matters most. People with claustrophobia should not book this activity, and anyone who dislikes enclosed spaces should think carefully before choosing it. The tour provider also says it is not suitable for people with epilepsy.

You should not feel pressured to take the final challenge. The abseiling, underground rooms, and audio-visual presentation already make a complete activity.

Guides, group size, and the pace of the tour

The experience lasts about 150 minutes and operates in English. Groups are limited to eight participants, a useful number for an activity that involves equipment, instructions, and individual descents.

A small group makes a practical difference here. You receive more direct contact with the instructors, and the team can keep an eye on each person’s technique. It also means you are not lost in a large crowd while waiting for your turn.

The guides include licensed instructors, and Sara and Marko have been specifically praised for being friendly, patient, and clear in their explanations. That combination matters more here than polished entertainment. You want someone who can explain the equipment, correct your technique, and stay calm if you hesitate at the rock face.

The tour has been rated 4.8 out of 5 from 12 ratings, with repeated praise for the professional instruction, warm manner of the staff, and strong mix of activity and history. The most useful point is not the number itself. It is the consistent emphasis on feeling safe while trying something new.

Allow time for the whole sequence. The 150 minutes includes instruction, practice, equipment, abseiling, the fortress walk, the special effects, and the closing activities. This is not a quick photo stop with a rope added on.

Is $88 a fair price?

At $88 per person, this is not the cheapest way to spend two and a half hours in Croatia. The price makes more sense when you consider what is included: entry to San Giovanni fortress, the guided underground tour, certified abseiling equipment, licensed professional instructors, insurance, audio-visual effects, and wine tasting.

You are paying for both access and supervision. A first-time abseiling session requires equipment, safety checks, instruction, and staff support. Here, those costs are joined to a guided visit at a distinctive historic site.

The value is strongest if you want variety. You get a physical activity, an unusual place, historical context, visual effects, and a social finish with wine. If you only want a quiet fortress visit, the rope work will be unnecessary. If you only want a serious climbing session, the historical and theatrical sections may feel like extras.

Private tours and other dates or times can be arranged on request. That may help if you are traveling with your own group or have a fixed schedule, but you will need to contact the provider directly.

What to wear and bring

Take the clothing rules seriously. The underground spaces stay at 14 to 16°C, so bring a warmer layer even when the weather outside is hot.

Your shoes must have non-slip soles. Hiking shoes are the safest choice, though sturdy sports shoes are also listed as suitable. Smooth-soled trainers are not appropriate for the uneven and potentially slippery rock, particularly on the Abseil Plus descent.

Bring:

• Hiking shoes or sturdy sports shoes with non-slip soles
• A warm layer for the underground sections
• Comfortable sports clothing
• A willingness to follow instructions closely

The agency may change or adjust the tour in bad weather. It can also refuse participation if you arrive with inadequate footwear or under the influence of alcohol or drugs. That is sensible for a rope activity, even if it is inconvenient at the last minute.

The tour and entry into the underground facility are undertaken at your own risk. The equipment and instruction reduce the practical risks, but they do not remove the need for care and personal judgment.

Who should book this experience?

I would choose this for an active couple, a small group of friends, or a solo visitor who wants something beyond the usual Croatian sightseeing route. You do not need previous abseiling experience, so beginners can take part without training beforehand.

It also suits people who like a little history with their adventure. The fortress gives the day a strong sense of place, while the rope work keeps it from becoming a passive underground walk.

The activity is not suitable for children under 10, people with claustrophobia, or people with epilepsy. You should also reconsider it if you dislike uneven rock, enclosed spaces, or being asked to make a controlled descent under instruction.

The tour is available in English, and the group size is limited to eight. If you want a private version or a different date and time, contact ADVENTURER through WhatsApp at +385 98 316 322.

Cancellation is flexible: you can cancel up to 24 hours before the activity for a full refund. You can also reserve now and pay later, which is useful if your Croatian plans are still shifting.

Should you book Abseil Plus?

Book it if you want a compact but varied adventure: beginner-level rope work, a little history, unusual underground architecture, special effects, a darkness challenge, and wine at the finish.

I especially recommend it to first-time abseilers who appreciate patient instruction. The gradual practice, instructor backup, and choice of difficulty make the activity approachable, while the cascading rock gives experienced or confident participants an extra challenge.

Skip it if you want a relaxed museum visit, dislike enclosed places, or do not have proper non-slip shoes. For everyone else, the $88 price is reasonable because you are getting far more than a single descent. You are spending 150 minutes inside a rare fortress setting with trained guides and several distinct parts to the experience.

FAQ

How long does the Tunnel Abseiling Plus tour last?

The tour lasts 150 minutes, or about two and a half hours.

Where does the tour take place?

It takes place in Zagreb County, Croatia, at the underground San Giovanni World War II fortress.

Do I need previous abseiling experience?

No. The tour is designed for beginners and starts with instruction, an equipment introduction, a horizontal practice exercise, and a demonstration.

What is the difference between Abseil and Abseil Plus?

Abseil includes the guided fortress visit and one or two beginner-friendly descents with different difficulty options. Abseil Plus adds a descent on cascading rock inside the fortress and may include a simultaneous descent in pairs.

What should I wear?

Bring warmer clothing because the underground temperature is 14 to 16°C. You must wear hiking shoes or sturdy sports shoes with non-slip soles.

Is the tour suitable for children?

The tour is not suitable for children under 10 years old.

Is the activity available in English?

Yes. The tour includes a live English-speaking guide and is limited to eight participants.